A087448 a(n) = 3^(n-1)*(n+3)/2 - (n-1)/2.

1, 2, 7, 26, 93, 322, 1091, 3642, 12025, 39362, 127935, 413338, 1328597, 4251522, 13551739, 43046714, 136314609, 430467202, 1355971703, 4261625370, 13366006861, 41841412802, 130754415027, 407953774906, 1270932914153, 3954013510722, 12285684836911, 38127987424922, 118196761017285

Offset

0,2

Comments

Binomial transform of A087447. Second binomial transform of 1,0,3,0,5,0,7,... (A005408).

Links

Paolo Xausa, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8,-22,24,-9).

Formula

G.f.: (1-2*x)*(1-4*x+5*x^2)/((1-x)^2*(1-3*x)^2). - Colin Barker, Mar 18 2012

Mathematica

A087448[n_] := (3^n*(n + 3) - 3*(n - 1))/6; Array[A087448, 30, 0] (* or *)
LinearRecurrence[{8, -22, 24, -9}, {1, 2, 7, 26}, 30] (* Paolo Xausa, Mar 04 2026 *)

Crossrefs

Cf. A005408, A087447.

Sequence in context: A000697 A027417 A134063 * A289449 A188860 A129273

Adjacent sequences: A087445 A087446 A087447 * A087449 A087450 A087451

Keyword

easy,nonn

Author

Paul Barry, Sep 05 2003

Extensions

More terms from Paolo Xausa, Mar 04 2026

Status

approved