OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
MAPLE
s:= n-> sort(map(i-> i[2], ifactors(n)[2])):
a:= proc(n) option remember; local k; for k from 1+
a(n-1) while s(k)<>s(numtheory[sigma](k)-k) do od; k
end: a(0):=0:
seq(a(n), n=1..80);
MATHEMATICA
okQ[k_] := !PrimeQ[k] && Sort[FactorInteger[k][[All, 2]]] == Sort[FactorInteger[DivisorSigma[1, k] - k][[All, 2]]];
Select[Range[1000], okQ] (* Jean-François Alcover, Nov 23 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 08 2018
STATUS
approved