A083231 a(n) = (3*5^n + (-3)^n)/4.

1, 3, 21, 87, 489, 2283, 11901, 58047, 294609, 1459923, 7338981, 36576807, 183238329, 915128763, 4578832461, 22884596367, 114451679649, 572172304803, 2861119804341, 14304824180727, 71526445426569, 357625253564043

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..300

Index entries for linear recurrences with constant coefficients, signature (2,15).

Formula

a(n) = (3*5^n + (-3)^n)/4.

G.f.: (1+x)/((1-5*x)*(1+3*x)).

E.g.f.: (3*exp(5*x) + exp(-3*x)/4.

Prog

(Magma) [(3*5^n+(-3)^n)/4: n in [0..25]]; // Vincenzo Librandi, Jun 29 2011

Crossrefs

Cf. A083232, A053524 (binomial transform, shifted).

Sequence in context: A253943 A034490 A071351 * A129755 A059826 A108970

Adjacent sequences: A083228 A083229 A083230 * A083232 A083233 A083234

Keyword

easy,nonn

Author

Paul Barry, Apr 23 2003

Status

approved