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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

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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.