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Revision History for A033502

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Carmichael numbers of the form (6*k+1)*(12*k+1)*(18*k+1), where 6*k+1, 12*k+1 and 18*k+1 are all primes.
(history; published version)
#53 by Peter Luschny at Thu Aug 04 05:08:11 EDT 2022
STATUS

proposed

approved

#52 by Jon E. Schoenfield at Wed Aug 03 22:30:48 EDT 2022
STATUS

editing

proposed

#51 by Jon E. Schoenfield at Wed Aug 03 22:20:05 EDT 2022
COMMENTS

All members terms of this sequence are primary Carmichael numbers (A324316) having the following remarkable property. Let m be a term of A033502. For each prime divisor p of m, the sum of the base-p digits of m equals p. This property also holds for "almost all" 3-term Carmichael numbers (A087788), since they can be represented by certain Chernick polynomials, whose values obey a strict s-decomposition (A324460) besides certain exceptions, see Kellner 2019. - _Bernd C. Kellner_, Aug 03 2022

the following remarkable property. Let m be an element of A033502. For each prime divisor p of m, the sum of the base-p digits of m equals p. This property also holds for "almost all" 3-term Carmichael numbers (A087788), since they can be represented by certain Chernick polynomials, whose values obey a strict s-decomposition (A324460) besides certain exceptions, see Kellner 2019. - Bernd C. Kellner, Aug 03 2022

PROG

(MAGMAMagma) [n : k in [1..710] | IsPrime(a) and IsPrime(b) and IsPrime(c) and IsOne(n mod CarmichaelLambda(n)) where n is a*b*c where a is 6*k+1 where b is 12*k+1 where c is 18*k+1]; // Arkadiusz Wesolowski, Oct 29 2013

STATUS

proposed

editing

Discussion
Wed Aug 03
22:30
Jon E. Schoenfield: I apologize for a question that may make it obvious that I know next to nothing about the subject matter at hand: Does the phrase “whose values obey a strict s-decomposition (A324460) besides certain exceptions” apply to all Chernick polynomials? (If so, then I think the comma before “whose” is okay.) Or does it apply only to “certain” Chernick polynomials? (If so, then I think the comma before “whose” should be deleted. I’m asking about this because of the differences in punctuation and meaning between restrictive and nonrestrictive clauses in English.) Thanks!
#50 by Bernd C. Kellner at Wed Aug 03 16:58:10 EDT 2022
STATUS

editing

proposed

#49 by Bernd C. Kellner at Wed Aug 03 16:42:20 EDT 2022
COMMENTS

Also called Chernick's Carmichael numbers. The polynomial (6*k+1)*(12*k+1)*(18*k+1) is the simplest Chernick polynomial. [Named after the American physicist and mathematician Jack Chernick (1911-1971). - Amiram Eldar, Jun 15 2021]

The first term, 1729, is the Hardy-Ramanujan number and the smallest primary Carmichael number (A324316).

All members of this sequence are primary Carmichael numbers (A324316) having

the following remarkable property. Let m be an element of A033502. For each prime divisor p of m, the sum of the base-p digits of m equals p. This property also holds for "almost all" 3-term Carmichael numbers (A087788), since they can be represented by certain Chernick polynomials, whose values obey a strict s-decomposition (A324460) besides certain exceptions, see Kellner 2019. - Bernd C. Kellner, Aug 03 2022

LINKS

Bernd C. Kellner and Jonathan Sondow, <a href="http://math.colgate.edu/~integers/v52/v52.pdf">On Carmichael and polygonal numbers, Bernoulli polynomials, and sums of base-p digits</a>, Integers 21 (2021), #A52, 21 pp.; arXiv:<a href="https://arxiv.org/abs/1902.10672">1902.10672</a> [math.NT], 2019.

Bernd C. Kellner, <a href="http://math.colgate.edu/~integers/w38/w38.pdf">On primary Carmichael numbers</a>, Integers 22 (2022), #A38, 39 pp.; arXiv:<a href="https://arxiv.org/abs/1902.11283">1902.11283</a> [math.NT], 2019.

CROSSREFS

Values of k are given by A046025. See also Subsequence of A002997, A087788, and A324316.

STATUS

approved

editing

Discussion
Wed Aug 03
16:44
Bernd C. Kellner: Comments and links updated.
#48 by Joerg Arndt at Tue Jun 15 07:31:31 EDT 2021
STATUS

reviewed

approved

#47 by Michel Marcus at Tue Jun 15 02:48:02 EDT 2021
STATUS

proposed

reviewed

#46 by Amiram Eldar at Tue Jun 15 02:45:15 EDT 2021
STATUS

editing

proposed

#45 by Amiram Eldar at Tue Jun 15 01:49:48 EDT 2021
REFERENCES

R. Richard K. Guy, Unsolved Problems in Number Theory, 3rd Edition, Springer, 2004, Section A13, pp. 50-53.

LINKS

Jack Chernick, <a href="http://projecteuclid.org/euclid.bams/1183501763">On Fermat's simple theorem</a>, Bull. Amer. Math. Soc. , Vol. 45:, No. 4 (1939), pp. 269-274.

D. Douglas E. Iannucci, <a href="http://math.colgate.edu/~integers/s77/s77.Abstract.html">When the small divisors of a natural number are in arithmetic progression</a>, INTEGERS, Electronic Journal of Combinatorial Number Theory, #77, Vol. 18 (2018), #77. See p. 9.

G. Tarry, I. Franel, A. Korselt, and G. Vacca. <a href="https://oeis.org/wiki/File:Probl%C3%A8me_chinois.pdf">Problème chinois</a>. L'intermédiaire des mathématiciens , Vol. 6 (1899), pp. 142-144.

Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CarmichaelNumber.html">Carmichael Number</a>.

<a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>.

#44 by Amiram Eldar at Tue Jun 15 01:46:03 EDT 2021
COMMENTS

Also called Chernick's Carmichael numbers. [Named after the American physicist and mathematician Jack Chernick (1911-1971). - _Amiram Eldar_, Jun 15 2021]

STATUS

approved

editing