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

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 :
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, 112, 1008, 3584, 5503, 3999, 1477, 284, 27, 1
0, 4, 128, 1392, 6400, 13440, 13842, 7483, 2216, 360, 30, 1

Crossrefs

Cf. Diagonals : A000012, A008585, A022266, A000007, A113311

Sequence in context: A212186 A274662 A186827 * A319083 A332099 A045406

Adjacent sequences: A207324 A207325 A207326 * A207328 A207329 A207330

Keyword

easy,nonn,tabl

Author

Philippe Deléham, Feb 17 2012

Status

approved