1,2

These are all the terms up to 10^8.

Table of n, a(n) for n=1..6.

sigma(2+1)/2 = 2, so 2 is a term of the sequence.

A110817:=proc(q)

local n;

for n from 1 to q do if (sigma(n+1) mod n)=0 then print(n); fi; od; end:

A110817 (10000000000); # Paolo P. Lava, Feb 26 2013

Select[Range[10^6], IntegerQ[DivisorSigma[1, # + 1]/# ] &]

Sequence in context: A295331 A064448 A173215 * A189428 A110860 A050995

Adjacent sequences: A110814 A110815 A110816 * A110818 A110819 A110820

nonn

Joseph L. Pe, Sep 15 2005

a(6) from Donovan Johnson, Nov 15 2009

approved