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A014901 a(1)=1, a(n) = 18*a(n-1) + n. 2
1, 20, 363, 6538, 117689, 2118408, 38131351, 686364326, 12354557877, 222382041796, 4002876752339, 72051781542114, 1296932067758065, 23344777219645184, 420205989953613327, 7563707819165039902, 136146740744970718253 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (20, -37, 18).

FORMULA

a(n) = -18/289 + (18/289)*18^n - (1/17)*n, with n >= 1. - Paolo P. Lava, Jan 14 2009

a(1)=1, a(2)=20, a(3)=363, a(n) = 20*a(n-1) - 37*a(n-2) + 18*a(n-3). - Vincenzo Librandi, Oct 20 2012

MATHEMATICA

LinearRecurrence[{20, -37, 18}, {1, 20, 363}, 20] (* Vincenzo Librandi, Oct 20 2012 *)

nxt[{n_, a_}]:={n+1, 18a+n+1}; NestList[nxt, {1, 1}, 20][[All, 2]] (* Harvey P. Dale, Oct 08 2017 *)

PROG

(MAGMA) I:=[1, 20, 363]; [n le 3 select I[n] else 20*Self(n-1) - 37*Self(n-2) + 18*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Oct 20 2012

(Maxima)

a[1]:1$

a[2]:20$

a[3]:363$

a[n]:=20*a[n-1]-37*a[n-2]+18*a[n-3]$

A014901(n):=a[n]$

makelist(A014901(n), n, 1, 30); /* Martin Ettl, Nov 06 2012 */

CROSSREFS

Sequence in context: A115100 A049683 A228330 * A290581 A000564 A178352

Adjacent sequences:  A014898 A014899 A014900 * A014902 A014903 A014904

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Olivier Gérard

STATUS

approved

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Last modified June 24 13:17 EDT 2019. Contains 324325 sequences. (Running on oeis4.)