A056076 Numbers k that divide sigma(k) + d(k), where d(k) is the number of divisors of k and sigma(k) is their sum.

1, 3, 14, 52, 60, 130, 184, 656, 5472, 8648, 12008, 34688, 2118656, 2500704, 33721216, 40575616, 59376256, 89397016, 99523456, 134438912, 150441856, 173706136, 283417216, 537346048, 1082640256, 6801628304, 91707741184

Offset: 1

Author

Robert G. Wilson v, Jul 26 2000

Keywords

• nonn

Comments

a(28) > 2*10^11. 14451706793984, 2258918614925312 and 9007202811510784 are also terms. - Donovan Johnson, Feb 10 2012

a(28) > 10^13. - Giovanni Resta, Nov 13 2019

Crossrefs

Cf. A000203, A000005.

Programs

Mathematica

Do[If[Mod[DivisorSigma[1,n]+DivisorSigma[0,n],n]==0,Print[n]],{n,1,10^8}]

PARI

for(n=1,10^8, if(Mod((sigma(n)+numdiv(n)), n)==0,print(n)))

Extensions

Corrected by Jason Earls, Aug 06 2001

Corrected by T. D. Noe, Nov 01 2006

a(25)-a(27) from Donovan Johnson, Dec 07 2008