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A127571 Triangle T(n,k) = phi(n/k)*sigma(k) if k divides n, else 0. 0
1, 1, 3, 2, 0, 4, 2, 3, 0, 7, 4, 0, 0, 0, 6, 2, 6, 4, 0, 0, 12, 6, 0, 0, 0, 0, 0, 8, 4, 6, 0, 7, 0, 0, 0, 15, 6, 0, 8, 0, 0, 0, 0, 0, 13, 4, 12, 0, 0, 6, 0, 0, 0, 0, 18 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..55.

FORMULA

T(n,k) = sum_{j=k..n} A054523(n,j)* A130208(j,k), product of the two infinite lower triangular matrices.

T(n,1) = A000010(n).

T(n,n) = A000203(n).

EXAMPLE

First few rows of the triangle are:

1;

1, 3;

2, 0, 4;

2, 3, 0, 7;

4, 0, 0, 0, 6;

2, 6, 4, 0, 0, 12;

...

CROSSREFS

Cf. A000203, A000010, A038040 (row sums), A054523.

Sequence in context: A005874 A129239 A224825 * A194662 A143612 A011231

Adjacent sequences:  A127568 A127569 A127570 * A127572 A127573 A127574

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jan 19 2007

STATUS

approved

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Last modified November 28 15:24 EST 2014. Contains 250363 sequences.