OFFSET
0,2
COMMENTS
Second differences are four times the entries of A009971. - R. J. Mathar, Oct 25 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..700
Index entries for linear recurrences with constant coefficients, signature (29,-55,27).
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
EXAMPLE
a(1) = (3^(3 + 3) - 26 - 27)/169 = 676/169 = 4.
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 *)
PROG
(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
(PARI) a(n)=(3^(3*n+3)-26*n-27)/169 \\ Charles R Greathouse IV, Jul 06 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Lagneau, Oct 24 2011
STATUS
approved
