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A131108 2*A007318 - A097806. 3
1, 1, 1, 2, 3, 1, 2, 6, 5, 1, 2, 8, 12, 7, 1, 2, 10, 20, 20, 9, 1, 2, 12, 30, 40, 30, 11, 1, 2, 14, 42, 70, 70, 42, 13, 1, 2, 16, 56, 112, 140, 112, 56, 15, 1, 15, 2, 18, 72, 168252, 252, 168, 72, 17, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Row sums = A095121: (1, 2, 6, 14, 30,...).

Triangle T(n,k), 0<=k<=n,read by rows given by [1,1,-2,1,0,0,0,0,0,0,0,...] DELTA [1,0,0,1,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938 . - Philippe Deléham, Dec 18 2007

LINKS

Table of n, a(n) for n=0..54.

FORMULA

Twice Pascal's triangle minus A097806, the pairwise operator.

G.f.: (1-x*y+x^2+x^2*y)/((-1+x+x*y)*(x*y-1)). - R. J. Mathar, Aug 11 2015

EXAMPLE

First few rows of the triangle are:

1;

1, 1;

2, 3, 1;

2, 6, 5, 1;

2, 8, 12, 7, 1;

2, 10, 20, 20, 9, 1;

...

CROSSREFS

Cf. A097806, A095121, A007318.

Sequence in context: A308173 A256910 A181176 * A128255 A154948 A109091

Adjacent sequences:  A131105 A131106 A131107 * A131109 A131110 A131111

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jun 15 2007

EXTENSIONS

Corrected by Philippe Deléham, Dec 17 2007

STATUS

approved

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Last modified October 22 04:25 EDT 2019. Contains 328315 sequences. (Running on oeis4.)