The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A262965

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A262965

Least number k such that k mod s = prime(n) where s is the sum of the distinct primes dividing k.
(history; published version)

#21 by N. J. A. Sloane at Fri Dec 10 11:25:55 EST 2021

STATUS

proposed

approved

#20 by Michel Marcus at Fri Dec 10 06:16:02 EST 2021

STATUS

editing

proposed

#19 by Michel Marcus at Fri Dec 10 06:15:59 EST 2021

COMMENTS

Many values of a(n) terms are numbers with two distinct prime divisors, exceptions being a(157) = 15465, a(254) = 25815, a(279) = 28695, a(303) = 31665, ... which have three prime distinct divisors, ...

STATUS

proposed

editing

#18 by Michael S. Branicky at Fri Dec 10 06:13:25 EST 2021

STATUS

editing

proposed

#17 by Michael S. Branicky at Fri Dec 10 06:13:17 EST 2021

EXAMPLE

a(5) = 26 because 26 = 2*13 => 26 mod (2+13) = 26 mod 15 = 11 = prime(5).

PROG

(Python)

from sympy import prime, primefactors

def a(n):

k, target = 2, prime(n)

while k%sum(primefactors(k)) != target: k += 1

return k

print([a(n) for n in range(1, 53)]) # Michael S. Branicky, Dec 10 2021

STATUS

approved

editing

#16 by N. J. A. Sloane at Mon Oct 26 22:27:55 EDT 2015

STATUS

editing

approved

#15 by N. J. A. Sloane at Mon Oct 26 22:27:46 EDT 2015

COMMENTS

Many values of a(n) are numbers with two distinct prime divisors, except exceptions being a(157) = 15465, a(254) = 25815, a(279) = 28695, a(303) = 31665, ... with which have three prime distinct divisors, ...

STATUS

proposed

editing

Discussion

Mon Oct 26

22:27

N. J. A. Sloane: edited comment

#14 by Michel Lagneau at Sun Oct 25 13:48:51 EDT 2015

STATUS

editing

proposed

Discussion

Sun Oct 25

13:49

Michel Lagneau: OK. Comments corrected.

#13 by Michel Lagneau at Sun Oct 25 13:48:22 EDT 2015

COMMENTS

A large majority Many values of a(n) are numbers with two distinct prime divisors, except a(157) = 15465, a(254) = 25815, a(279) = 28695, a(303) = 31665, ... with three prime distinct divisors, ...

STATUS

reviewed

editing

#12 by Danny Rorabaugh at Fri Oct 23 23:49:35 EDT 2015

STATUS

proposed

reviewed

Discussion

Sun Oct 25

09:43

Wesley Ivan Hurt: In Comments: A large majority of a(n) --> Many values of a(n)