0,2

a(n) = n unless n is nonsquarefree, in which case a(n) = rank of n as a nonsquarefree number. Row sums of A105586.

Table of n, a(n) for n=0..74.

a(n) = Sum_{k=0..n} binomial(abs(mu(n)), abs(mu(k))).

a(4) = 1 since 4 is the first nonsquarefree number;

a(8) = 2 since 8 is the second nonsquarefree number.

Sequence in context: A001438 A342410 A345937 * A345998 A319676 A049073

Adjacent sequences: A105584 A105585 A105586 * A105588 A105589 A105590

easy,nonn

Paul Barry, Apr 14 2005

approved