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A168418 a(n) = 9*n - a(n-1) - 8 with n>1, a(1)=5. 2
5, 5, 14, 14, 23, 23, 32, 32, 41, 41, 50, 50, 59, 59, 68, 68, 77, 77, 86, 86, 95, 95, 104, 104, 113, 113, 122, 122, 131, 131, 140, 140, 149, 149, 158, 158, 167, 167, 176, 176, 185, 185, 194, 194, 203, 203, 212, 212, 221, 221, 230, 230, 239, 239, 248, 248, 257 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

FORMULA

a(n) = (18*n - 9*(-1)^n - 7)/4. - Paolo P. Lava, Nov 27 2009

From R. J. Mathar, Jan 26 2010: (Start)

a(n) = A168213(n-1), n>1.

G.f.: x*(5 + 4*x^2)/((1+x)*(x-1)^2). (End)

From G. C. Greubel, Jul 22 2016: (Start)

a(n) = a(n-1) + a(n-2) - a(n-3).

E.g.f.: (1/4)*(-9 + 16*exp(x) + (18*x - 7)*exp(2*x))*exp(-x). (End)

MATHEMATICA

LinearRecurrence[{1, 1, -1}, {5, 5, 14}, 60] (* Vincenzo Librandi, Feb 27 2012 *)

PROG

(MAGMA) I:=[5, 5, 14]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..60]]; // Vincenzo Librandi, Feb 28 2012

CROSSREFS

Sequence in context: A252768 A062367 A286257 * A266440 A294750 A247940

Adjacent sequences:  A168415 A168416 A168417 * A168419 A168420 A168421

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Nov 25 2009

STATUS

approved

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Last modified November 18 19:06 EST 2017. Contains 294894 sequences.