A147720 - OEIS

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A147720

Riordan array (1, x(1-x)/(1-3x)).

1, 0, 1, 0, 2, 1, 0, 6, 4, 1, 0, 18, 16, 6, 1, 0, 54, 60, 30, 8, 1, 0, 162, 216, 134, 48, 10, 1, 0, 486, 756, 558, 248, 70, 12, 1, 0, 1458, 2592, 2214, 1168, 410, 96, 14, 1, 0, 4374, 8748, 8478, 5160, 2150, 628, 126, 16

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OFFSET

0,5

COMMENTS

Array [0,2,1,0,0,0,....] DELTA [1,0,0,0,......] for Deléham DELTA as in A084938.

Row sums are A001835. Diagonal sums are related to A030186.

Row sums of inverse are essentially A091593. A147720*A007318 is A147721.

LINKS

Indranil Ghosh, Rows 0..100, flattened

FORMULA

Sum_{k=0..n} T(n,k)*x^k = A000007(n), A001835(n), A147722(n), A084120(n) for x = 0, 1, 2, 3 respectively. - Philippe Deléham, Nov 15 2008

G.f.: (1-3*x)/(1-(3+y)*x+y*x^2). - Philippe Deléham, Feb 15 2012

EXAMPLE

Triangle begins

0, 1;

0, 2, 1;

0, 6, 4, 1;

0, 18, 16, 6, 1;

0, 54, 60, 30, 8, 1;

0, 162, 216, 134, 48, 10, 1;

MATHEMATICA

nmax=9; Flatten[CoefficientList[Series[CoefficientList[Series[(1-3*x)/(1-(3+y)*x+y*x^2), {x, 0, nmax}], x], {y, 0, nmax}], y]] (* Indranil Ghosh, Mar 10 2017, after Philippe Deléham *)

CROSSREFS

Sequence in context: A262071 A011312 A275328 * A205813 A127631 A122538

Adjacent sequences: A147717 A147718 A147719 * A147721 A147722 A147723

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Nov 11 2008

STATUS

approved