The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A086471

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A086471

Product of distinct (smallest) prime signature divisors. In case of two or more divisors with the same prime signature the smallest is considered to evaluate the product.
(history; published version)

#16 by OEIS Server at Thu Jul 25 03:24:17 EDT 2024

LINKS

Amiram Eldar, <a href="/A086471/b086471_1.txt">Table of n, a(n) for n = 1..10000</a>

#15 by Michel Marcus at Thu Jul 25 03:24:17 EDT 2024

STATUS

reviewed

approved

Discussion

Thu Jul 25

03:24

OEIS Server: Installed first b-file as b086471.txt.

#14 by Joerg Arndt at Thu Jul 25 03:22:54 EDT 2024

STATUS

proposed

reviewed

#13 by Amiram Eldar at Thu Jul 25 03:18:53 EDT 2024

STATUS

editing

proposed

#12 by Amiram Eldar at Thu Jul 25 03:18:46 EDT 2024

COMMENTS

a(p) = p and a(p^r) = p^(T(r)) where p is a prime and T(r) = the r-th triangular number = r(r+1)/2.

FORMULA

a(p) = p and a(p^r) = p^(T(r)) where p is a prime and T(r) = the r-th triangular number = r(r+1)/2.

STATUS

reviewed

editing

Discussion

Thu Jul 25

03:18

Amiram Eldar: Yes. Moved.

#11 by Joerg Arndt at Thu Jul 25 00:50:44 EDT 2024

STATUS

proposed

reviewed

Discussion

Thu Jul 25

03:17

Michel Marcus: comment is a formula ?

#10 by Amiram Eldar at Thu Jul 25 00:29:35 EDT 2024

STATUS

editing

proposed

#9 by Amiram Eldar at Thu Jul 25 00:27:40 EDT 2024

LINKS

Amiram Eldar, <a href="/A086471/b086471_1.txt">Table of n, a(n) for n = 1..10000</a>

#8 by Amiram Eldar at Thu Jul 25 00:27:27 EDT 2024

MATHEMATICA

a[n_] := Module[{d = Rest[Divisors[n]]}, Times @@ DeleteDuplicatesBy[{#, Sort[FactorInteger[#][[;; , 2]]]} & /@ d, Last][[;; , 1]]]; Array[a, 60] (* Amiram Eldar, Jul 25 2024 *)

STATUS

approved

editing

#7 by Susanna Cuyler at Sat Mar 07 20:17:27 EST 2020

STATUS

proposed

approved