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A143418 Triangle read by rows. T(n,k) = binomial(n,k)*(binomial(n,k)-1)/2. 3
1, 3, 3, 6, 15, 6, 10, 45, 45, 10, 15, 105, 190, 105, 15, 21, 210, 595, 595, 210, 21, 28, 378, 1540, 2415, 1540, 378, 28, 36, 630, 3486, 7875, 7875, 3486, 630, 36, 45, 980, 7140, 21945, 31626, 21945, 7140, 980, 45, 55, 1485, 27060, 54285, 106491, 106491 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row sums = A108958: (1, 6, 27, 110, 430, 1652, ...).

LINKS

Table of n, a(n) for n=1..51.

FORMULA

T(n,k) = A065420(n-1,k-1)/2. - R. J. Mathar, Apr 04 2012

EXAMPLE

Row 4 of Pascal's triangle (1, 4, 6, 4, 1) with each term squared = (1, 16, 36, 16, 1), then subtracting (1, 4, 6, 4, 1) = (0, 12, 30, 12, 0). Dividing by 2 and deleting the zeros, we get row 4 of A143148: (6, 15, 6).

First few rows of the triangle =

1;

3, 3;

6, 15, 6;

10, 45, 45, 10;

15, 105, 190, 105, 15;

21, 210, 595, 595, 210, 21;

28, 378, 1540, 2415, 1540, 378, 28;

...

MAPLE

A143418 := proc(n, k)

        binomial(n, k)*(binomial(n, k)-1)/2 ;

end proc:

seq(seq(A143418(n, k), k=1..n-1), n=1..12) ; # R. J. Mathar, Apr 04 2012

CROSSREFS

Cf. A007318, A108958.

Sequence in context: A325865 A110523 A145597 * A336452 A092370 A245796

Adjacent sequences:  A143415 A143416 A143417 * A143419 A143420 A143421

KEYWORD

nonn,easy,tabl

AUTHOR

Gary W. Adamson and Roger L. Bagula, Aug 14 2008

STATUS

approved

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Last modified June 13 22:46 EDT 2021. Contains 345016 sequences. (Running on oeis4.)