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A158824 Triangle T(n,1) = A000292(n) and T(n,k) = (k-1)*(k-n-1)*(k-n-2)/2 if 2<=k<=n. 2
1, 4, 1, 10, 3, 2, 20, 6, 6, 3, 35, 10, 12, 9, 4, 56, 15, 20, 18, 12, 5, 84, 21, 30, 30, 24, 15, 6, 120, 28, 42, 42, 40, 30, 18, 7, 165, 36, 56, 63, 60, 50, 36, 21, 8, 220, 45, 72, 84, 84, 75, 60, 42, 24, 9, 286, 55, 90, 108, 112, 105, 90, 70, 48, 27, 10 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The triangle can also be defined by multiplying the triangles A(n,k)=1 and A158823(n,k), that is, this here are the partial column sums of A158823.

LINKS

Table of n, a(n) for n=1..66.

EXAMPLE

First few rows of the triangle =

1;

4, 1;

10, 3, 2;

20, 6, 6, 3;

35, 10, 12, 9, 4;

56, 15, 20, 18, 12, 5;

84, 21, 30, 30, 24, 15, 6;

120, 28, 42, 45, 40, 30, 18, 7;

165, 36, 56, 63, 60, 50, 36, 21, 8;

220, 45, 72, 84, 84, 75, 60, 42, 24, 9;

286, 55, 90, 108, 112, 105, 90, 70, 48, 27, 10;

364, 66, 110, 135, 144, 140, 126, 105, 80, 54, 30, 11;

455, 78, 132, 165, 180, 180, 168, 147, 120, 90, 60, 33, 12;

...

CROSSREFS

Cf. A104633, A062707, A158823, A000332 (row sums).

Sequence in context: A006370 A262370 A108759 * A039806 A030320 A104713

Adjacent sequences:  A158821 A158822 A158823 * A158825 A158826 A158827

KEYWORD

nonn,tabl,easy

AUTHOR

Gary W. Adamson & Roger L. Bagula, Mar 28 2009

STATUS

approved

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Last modified December 15 15:01 EST 2019. Contains 329999 sequences. (Running on oeis4.)