A213556 Principal diagonal of the convolution array A213555.
1, 19, 118, 446, 1271, 3017, 6300, 11964, 21117, 35167, 55858, 85306, 126035, 181013, 253688, 348024, 468537, 620331, 809134, 1041334, 1324015, 1664993, 2072852, 2556980, 3127605, 3795831, 4573674, 5474098, 6511051, 7699501
Offset: 1
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).
Programs
-
Mathematica
(See A213553.)
Formula
a(n) = (9*n^5 + 15*n^4 + 5*n^3 + n)/30.
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 + 13*x + 19*x^2 + 3*x^3)/(1 - x)^6.