A199417 (3*7^n+1)/2.

2, 11, 74, 515, 3602, 25211, 176474, 1235315, 8647202, 60530411, 423712874, 2965990115, 20761930802, 145333515611, 1017334609274, 7121342264915, 49849395854402, 348945770980811, 2442620396865674, 17098342778059715

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8,-7).

Formula

a(n) = 7*a(n-1)-3.

a(n) = 8*a(n-1)-7*a(n-2).

G.f.: (2-5*x)/((1-x)*(1-7*x)).

Mathematica

(3*7^Range[0, 30]+1)/2 (* or *) LinearRecurrence[{8, -7}, {2, 11}, 30] (* Harvey P. Dale, Nov 20 2012 *)

Prog

(Magma) [(3*7^n+1)/2: n in [0..30]];

Crossrefs

Sequence in context: A074609 A299786 A335310 * A114179 A231556 A207397

Adjacent sequences: A199414 A199415 A199416 * A199418 A199419 A199420

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 06 2011

Status

approved