A155604 a(n) = 6^n + 3^n - 1.

1, 8, 44, 242, 1376, 8018, 47384, 282122, 1686176, 10097378, 60525224, 362974202, 2177313776, 13062288338, 78368947064, 470199333482, 2821152954176, 16926788584898, 101560344088904, 609360902271962, 3656161926847376

Offset: 0

Author

Mohammad K. Azarian, Jan 25 2009

Keywords

• nonn
• easy

Links

• Paolo Xausa, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (10,-27,18).

Crossrefs

Cf. A074501, A020515, A155588, A155590, A155592, A155593, A155594, A155596, A155597, A155598, A155599, A155600, A155601, A155602, A155603.

Programs

Mathematica

Table[6^n + 3^n - 1, {n, 0, 25}] (* Paolo Xausa, Aug 21 2024 *)

PARI

a(n)=6^n+3^n-1 \\ Charles R Greathouse IV, Jun 11 2015

Formula

G.f.: 1/(1-6*x)+1/(1-3*x)-1/(1-x).

E.g.f.: exp(6*x)+exp(3*x)-exp(x).

a(n) = 9*a(n-1)-18*a(n-2)-10 with a(0) = 1, a(1) = 8. - Vincenzo Librandi, Jul 21 2010