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A056076 Numbers n such that n divides sigma(n) + d(n), where d(n) is the number of divisors of n and sigma(n) is their sum. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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

LINKS

Table of n, a(n) for n=1..27.

MAPLE

with(numtheory); A056076:=proc(q)  local n;

for n from 1 to q do if type((sigma(n)+tau(n))/n, integer) then print(n); fi; od; end:  A056076(10^10); # Paolo P. Lava, Apr 29 2013

MATHEMATICA

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

PROG

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

CROSSREFS

Cf. A000203, A000005.

Sequence in context: A320826 A322199 A192882 * A117133 A238226 A083874

Adjacent sequences:  A056073 A056074 A056075 * A056077 A056078 A056079

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jul 26 2000

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

STATUS

approved

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Last modified May 6 19:52 EDT 2021. Contains 343586 sequences. (Running on oeis4.)