A105587 - OEIS

A105587

Row sums of a Möbius-binomial triangle.

1, 2, 3, 4, 1, 6, 7, 8, 2, 3, 11, 12, 4, 14, 15, 16, 5, 18, 6, 20, 7, 22, 23, 24, 8, 9, 27, 10, 11, 30, 31, 32, 12, 34, 35, 36, 13, 38, 39, 40, 14, 42, 43, 44, 15, 16, 47, 48, 17, 18, 19, 52, 20, 54, 21, 56, 22, 58, 59, 60, 23, 62, 63, 24, 25, 66, 67, 68, 26, 70, 71, 72, 27, 74, 75

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

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

LINKS

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

FORMULA

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

EXAMPLE

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

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

CROSSREFS

Sequence in context: A001438 A342410 A345937 * A345998 A319676 A049073

Adjacent sequences: A105584 A105585 A105586 * A105588 A105589 A105590

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Apr 14 2005

STATUS

approved