A291390 a(n) = (1/5)*A291389(n).

2, 17, 130, 940, 6550, 44475, 296250, 1944375, 12612500, 81035000, 516537500, 3270615625, 20591031250, 128998328125, 804673593750, 5000444062500, 30969644531250, 191231146484375, 1177627753906250, 7234317013671875, 44342955390625000, 271252632343750000

Offset: 0

Author

Clark Kimberling, Sep 06 2017

Keywords

• nonn
• easy

Links

• Clark Kimberling, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (10, -15, -50, -25)

Crossrefs

Cf. A019590, A291382, A291389.

Programs

Mathematica

z = 60; s = x + x^2; p = (1 - 5 s)^2;
Drop[CoefficientList[Series[s, {x, 0, z}], x], 1]  (* A019590 *)
u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1]  (* A291389 *)
u / 5  (* A291390 *)

Formula

G.f.: -(((1 + x) (-2 + 5 x + 5 x^2))/(-1 + 5 x + 5 x^2)^2).

a(n) = 10*a(n-1) - 15*a(n-2) - 50*a(n-3) - 25*a(n-4) for n >= 5.