OFFSET
1,3
LINKS
FORMULA
Additive with a(2^e) = -e, and for odd primes p, a(p^2e) = 0, a(p^(2e-1)) = A007814(1+p) + A007814(e). - Antti Karttunen, Nov 23 2023
MATHEMATICA
a[n_] := IntegerExponent[DivisorSigma[1, n], 2] - IntegerExponent[n, 2]; Array[a, 100] (* Amiram Eldar, Mar 03 2023 *)
PROG
(PARI) A361025(n) = (valuation(sigma(n), 2) - valuation(n, 2));
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, Mar 03 2023
STATUS
approved