A027849 a(n) = (n+1)*(5*n^2+4*n+1).

1, 20, 87, 232, 485, 876, 1435, 2192, 3177, 4420, 5951, 7800, 9997, 12572, 15555, 18976, 22865, 27252, 32167, 37640, 43701, 50380, 57707, 65712, 74425, 83876, 94095, 105112, 116957, 129660, 143251

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Crossrefs

Cf. A260260 (comment). [Bruno Berselli, Jul 22 2015]

Formula

From Chai Wah Wu, Jun 10 2016: (Start)

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n > 3.

G.f.: (13*x^2 + 16*x + 1)/(x - 1)^4. (End)