A217783 Expansion of (1-x)*(1-2x)/((1-5x+5*x^2)*(1-3x+x^2)).

1, 5, 21, 83, 318, 1196, 4445, 16389, 60097, 219527, 799734, 2907800, 10558041, 38297573, 138819053, 502925211, 1821362830, 6594366404, 23870720757, 86396702117, 312668994969, 1131463798415, 4094241931526, 14814592074288, 53603587025713, 193949782284101

Offset: 0

Author

Philippe Deléham, Mar 24 2013

Keywords

• nonn
• easy

Comments

A diagonal of the square array A217770.

Links

• Index entries for linear recurrences with constant coefficients, signature (8, -21, 20, -5).

Crossrefs

Cf. A217770, A217777, A217778, A217779, A217782.

Formula

a(n) = A217770(n,n+3).

a(n) = 8*a(n-1) -21*a(n-2) + 20*a(n-3) -5*a(n-4) for n>=4, a(0) = 1, a(1) = 5, a(2) = 21, a(3) = 83.