OFFSET
1,3
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
MATHEMATICA
s[n_] := DivisorSum[n, (# + 1) * Mod[#, 2] &] / 2; a[1] = 1; a[n_] := a[n] = -DivisorSum[n, a[#] * s[n/#] &, # < n &]; Array[a, 100] (* Amiram Eldar, Dec 08 2021 *)
PROG
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, Dec 07 2021
STATUS
approved