OFFSET
1,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: (Sum_{k>=1} mu(k)^2 * k * x^k) / (1 + x).
a(n) = -a(n-1) + |A055615(n)| for n > 1.
PROG
(PARI) a(n) = sum(k=1, n, (-1)^(n-k)*k*moebius(k)^2);
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Apr 05 2023
STATUS
approved