The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A065765 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A065765

Sum of divisors of twice square numbers.
(history; published version)

#21 by Michael De Vlieger at Fri Oct 28 07:15:07 EDT 2022

STATUS

reviewed

approved

#20 by Joerg Arndt at Fri Oct 28 06:19:27 EDT 2022

STATUS

proposed

reviewed

#19 by Amiram Eldar at Fri Oct 28 05:35:53 EDT 2022

STATUS

editing

proposed

#18 by Amiram Eldar at Fri Oct 28 05:14:41 EDT 2022

FORMULA

Sum_{k=1..n} a(k) ~ c * n^3, where c = 12*zeta(3)/Pi^2 = 1.461525... . - Amiram Eldar, Oct 28 2022

CROSSREFS

Cf. A000203, A000290, A002117, A028982, A065766, A097022.

#17 by Amiram Eldar at Fri Oct 28 05:14:12 EDT 2022

FORMULA

a(n) = 3*A065766(n).

CROSSREFS

Cf. A028982, A000203, A000290, A028982, A065766, A097022.

STATUS

approved

editing

#16 by Joerg Arndt at Sun Jun 17 02:50:09 EDT 2018

STATUS

proposed

approved

#15 by Jon E. Schoenfield at Sun Jun 17 02:46:03 EDT 2018

STATUS

editing

proposed

#14 by Jon E. Schoenfield at Sun Jun 17 02:45:59 EDT 2018

LINKS

T. D. Noe, <a href="/A065765/b065765.txt">Table of n, a(n) for n = 1..10000</a>

FORMULA

a(n) =Sigma[ sigma(2*n^2]) = A000203[(2*A000290(n)]).

a(n) = 3*A065766(n)

PROG

(PARI) { for (n=1, 10000, write("b065765.txt", n, " ", sigma(2*n^2)) ) } [From _\\ _Harry J. Smith_, Oct 30 2009]

CROSSREFS

Cf. A028982, A000203, A000290.

STATUS

approved

editing

#13 by Harvey P. Dale at Sun Sep 06 16:50:15 EDT 2015

STATUS

editing

approved

#12 by Harvey P. Dale at Sun Sep 06 16:50:11 EDT 2015

MATHEMATICA

DivisorSigma[1, 2*Range[50]^2] (* Harvey P. Dale, Sep 06 2015 *)

STATUS

approved

editing