OFFSET
1,3
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
FORMULA
MATHEMATICA
A011772[n_] := Module[{m = 1}, While[Not[IntegerQ[m(m+1)/(2n)]], m++]; m];
a[n_] := DivisorSigma[1, n] - A011772[n];
Array[a, 100] (* Jean-François Alcover, Jun 12 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 30 2021
STATUS
approved