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A014918 a(1)=1, a(n) = n*6^(n-1) + a(n-1). 2
1, 13, 121, 985, 7465, 54121, 380713, 2620201, 17736745, 118513705, 783641641, 5137206313, 33435376681, 216285092905, 1391747554345, 8914707307561, 56873575734313, 361553445739561, 2291192622439465, 14478387422649385 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (13, -48, 36).

FORMULA

a(n) = (1/25)*(1 - 6^n*(5*n-1)). - Paolo P. Lava, Jan 13 2009

a(1)=1, a(2)=13, a(n) = 12*a(n-1) - 36*a(n-2) + 1. - Vincenzo Librandi, Oct 23 2012

G.f.: x/((1-x)*(1-6*x)^2). - Vincenzo Librandi, Oct 23 2012

MAPLE

a:=n->sum (6^n-6^j, j=0..n): seq(a(n)/5, n=1..31); # Zerinvary Lajos, Dec 14 2008

MATHEMATICA

CoefficientList[Series[1/((1 - x)(1 - 6*x)^2), {x, 0, 40}], x] (* Vincenzo Librandi, Oct 23 2012 *)

nxt[{n_, a_}]:={n+1, (n+1*6^n+a}; Transpose[NestList[nxt, {1, 1}, 20]][[2]] (* or *) LinearRecurrence[{13, -48, 36}, {1, 13, 121}, 20] (* Harvey P. Dale, Apr 08 2014 *)

PROG

(MAGMA) I:=[1, 13]; [n le 2 select I[n] else 12*Self(n-1)-36*Self(n-2)+1: n in [1..30]]; // Vincenzo Librandi, Oct 23 2012

CROSSREFS

Sequence in context: A188709 A054962 A297394 * A081033 A091111 A196921

Adjacent sequences:  A014915 A014916 A014917 * A014919 A014920 A014921

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified October 23 16:20 EDT 2021. Contains 348215 sequences. (Running on oeis4.)