The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A325470

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

A325470

a(n) is the sum of divisors d of n such that d divides sigma(d).
(history; published version)

#12 by Charles R Greathouse IV at Thu Sep 08 08:46:24 EDT 2022

PROG

(MAGMAMagma) [&+[d: d in Divisors(n) | IsIntegral(SumOfDivisors(d) / d)] : n in [1..100]]

Discussion

Thu Sep 08

08:46

OEIS Server: https://oeis.org/edit/global/2944

#11 by Sean A. Irvine at Fri Aug 23 19:28:20 EDT 2019

STATUS

reviewed

approved

#10 by Antti Karttunen at Thu Aug 22 09:18:30 EDT 2019

STATUS

proposed

reviewed

#9 by Antti Karttunen at Thu Aug 22 09:17:44 EDT 2019

STATUS

editing

proposed

#8 by Antti Karttunen at Thu Aug 22 09:10:17 EDT 2019

LINKS

Antti Karttunen, <a href="/A325470/b325470.txt">Table of n, a(n) for n = 1..20000</a>

STATUS

proposed

editing

#7 by Amiram Eldar at Sat Aug 17 03:08:39 EDT 2019

STATUS

editing

proposed

#6 by Amiram Eldar at Sat Aug 17 03:07:34 EDT 2019

MATHEMATICA

a[n_] := DivisorSum[n, # &, Divisible[DivisorSigma[1, #], #] &]; Array[a, 100] (* Amiram Eldar, Aug 17 2019 *)

STATUS

proposed

editing

#5 by Andrew Howroyd at Fri Aug 16 19:56:42 EDT 2019

STATUS

editing

proposed

#4 by Andrew Howroyd at Fri Aug 16 19:56:36 EDT 2019

PROG

(PARI) a(n)={sumdiv(n, d, if(sigma(d) % d == 0, d))} \\ Andrew Howroyd, Aug 16 2019

STATUS

proposed

editing

#3 by Jaroslav Krizek at Fri Aug 16 19:27:29 EDT 2019

STATUS

editing

proposed