OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..61
EXAMPLE
After a(4)=6, with sigma(6)=12, the smallest number k such that sigma(k) is a multiple of 12 is 11, with sigma(11)=12. Thus a(5)=11.
MATHEMATICA
msa[n_]:=Module[{s1=DivisorSigma[1, n], n2=n+1}, While[Mod[DivisorSigma[1, n2], s1]!=0, n2++]; n2]; NestList[msa, 1, 60] (* Harvey P. Dale, Mar 20 2020 *)
PROG
(PARI) lista(nn) = {a = 1; print1(a, ", "); for (n = 1, nn, sa = sigma(a); a++; while (sigma(a) % sa, a++); print1(a, ", "); ); } \\ Michel Marcus, Oct 12 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Dec 09 2003
EXTENSIONS
Corrected, extended and edited by John W. Layman, Aug 10 2004
STATUS
approved