A207327 - OEIS

A207327

Riordan array (1, x*(1+x)^2/(1-x)).

1, 0, 1, 0, 3, 1, 0, 4, 6, 1, 0, 4, 17, 9, 1, 0, 4, 32, 39, 12, 1, 0, 4, 48, 111, 70, 15, 1, 0, 4, 64, 240, 268, 110, 18, 1, 0, 4, 80, 432, 769, 530, 159, 21, 1, 0, 4, 96, 688, 1792, 1905, 924, 217, 24, 1, 0, 4

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OFFSET

0,5

COMMENTS

Triangle T(n,k), read by rows, given by (0, 3, -5/3, 4/15, -3/5, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.

Row sums are A077995(n).

LINKS

Table of n, a(n) for n=0..56.

FORMULA

T(2*n,n) = A119259(n).

G.f.: (1-x)/(1-(1+y)*x-2*y*x^2-y*x^3).

T(n,k) = T(n-1,k) + T(n-1,k-1) + 2*T(n-2,k-1) + T(n-3,k-1), T(0,0) = 1, T(1,0) = 0.

EXAMPLE

Triangle begins :

0, 1

0, 3, 1

0, 4, 6, 1