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

Offset: 0

Author

Paul Barry, Apr 14 2005

Keywords

• easy
• nonn

Comments

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

Examples

			a(4) = 1 since 4 is the first nonsquarefree number;
a(8) = 2 since 8 is the second nonsquarefree number.
		

Formula

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