A213552 Principal diagonal of the convolution array A213551.

1, 15, 81, 281, 756, 1722, 3486, 6462, 11187, 18337, 28743, 43407, 63518, 90468, 125868, 171564, 229653, 302499, 392749, 503349, 637560, 798974, 991530, 1219530, 1487655, 1800981, 2164995, 2585611, 3069186, 3622536, 4252952

Offset

1,2

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).

Formula

a(n) = n*(1 + n)*(2 + n)(-3 + 7*n + 16*n^2)/120.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).

G.f.: x*(1 + 9*x + 6*x^2)/(1 - x)^6.

Mathematica

(See A213551.)

Crossrefs

Cf. A213551, A213500.

Sequence in context: A344722 A309336 A266288 * A060581 A253222 A334244

Adjacent sequences: A213549 A213550 A213551 * A213553 A213554 A213555

Keyword

nonn,easy

Author

Clark Kimberling, Jun 17 2012

Status

approved