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A117380 Riordan array (1/(1-4*x*c(x)),xc(x)), c(x) the g.f. of A000108. 2
1, 4, 1, 20, 5, 1, 104, 26, 6, 1, 548, 137, 33, 7, 1, 2904, 726, 178, 41, 8, 1, 15432, 3858, 954, 228, 50, 9, 1, 82128, 20532, 5100, 1242, 288, 60, 10, 1, 437444, 109361, 27233, 6701, 1601, 359, 71, 11, 1, 2331128, 582782, 145338, 35977, 8744, 2043, 442, 83, 12 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Triangle factors as (1,xc(x))*(1/(1-4x),x). Inverse of A117377. First row is A076035. Second row is A076025(n)-0^n. Row sums are A076025(n+1). Diagonal sums are A117381.

LINKS

Table of n, a(n) for n=0..53.

FORMULA

Number triangle T(0,0)=1, T(n,k)=[k<=n]*sum{j=0..n, (j/(n-j))*C(2n-j,n-j)[k<=j]*4^(j-k)}

EXAMPLE

Triangle begins

1,

4, 1,

20, 5, 1,

104, 26, 6, 1,

548, 137, 33, 7, 1,

2904, 726, 178, 41, 8, 1

Production array begins

4, 1

4, 1, 1

4, 1, 1, 1

4, 1, 1, 1, 1

4, 1, 1, 1, 1, 1

4, 1, 1, 1, 1, 1, 1

4, 1, 1, 1, 1, 1, 1, 1

4, 1, 1, 1, 1, 1, 1, 1, 1

... - Philippe Deléham, Mar 05 2013

CROSSREFS

Sequence in context: A128041 A144885 A144886 * A185420 A167432 A201639

Adjacent sequences:  A117377 A117378 A117379 * A117381 A117382 A117383

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Mar 10 2006

STATUS

approved

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Last modified February 18 00:19 EST 2019. Contains 320237 sequences. (Running on oeis4.)