A198080 a(n) = (3^(3*n + 3)- 26*n - 27)/169.

0, 4, 116, 3144, 84904, 2292428, 61895580, 1671180688, 45121878608, 1218290722452, 32893849506244, 888133936668632, 23979616290053112, 647449639831434076, 17481140275448720108, 471990787437115442976, 12743751260802116960416, 344081284041657157931300

Offset: 0

Author

Michel Lagneau, Oct 24 2011

Keywords

• nonn
• easy

Comments

Second differences are four times the entries of A009971. - R. J. Mathar, Oct 25 2011

Examples

			a(1) = (3^(3 + 3) - 26 - 27)/169 = 676/169 = 4.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..700
• Index entries for linear recurrences with constant coefficients, signature (29,-55,27).

Programs

Magma

I:=[0, 4, 116]; [n le 3 select I[n] else 29*Self(n-1)-55*Self(n-2)+27*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Nov 25 2011

Maple

for n from 0 to 30 do:x:=(3^(3*n+3) - 26*n - 27)/169  :  printf(`%d, `, x):od:

Mathematica

LinearRecurrence[{29,-55,27},{0,4,116},50] (* Vincenzo Librandi, Nov 25 2011 *)

PARI

a(n)=(3^(3*n+3)-26*n-27)/169 \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(n) = (3^(3*n + 3) - 26*n - 27)/169.

G.f.: -4*x / ( (27*x-1)*(x-1)^2 ). - R. J. Mathar, Oct 25 2011