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A168199 a(n) = 3*n - a(n-1) + 1 with n > 1, a(1)=2. 3
2, 5, 5, 8, 8, 11, 11, 14, 14, 17, 17, 20, 20, 23, 23, 26, 26, 29, 29, 32, 32, 35, 35, 38, 38, 41, 41, 44, 44, 47, 47, 50, 50, 53, 53, 56, 56, 59, 59, 62, 62, 65, 65, 68, 68, 71, 71, 74, 74, 77, 77, 80, 80, 83, 83, 86, 86, 89, 89, 92, 92, 95, 95, 98, 98, 101, 101, 104, 104, 107 (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) = (6*n + 5 + 3*(-1)^n)/4. - Jon E. Schoenfield, Jun 24 2010

G.f.: x*(2-x)*(1+2*x)/((1+x)*(1-x)^2). - Bruno Berselli, Feb 28 2012

MATHEMATICA

LinearRecurrence[{1, 1, -1}, {2, 5, 5}, 70] (* Vincenzo Librandi, Feb 28 2012 *)

PROG

(MAGMA) I:=[2, 5, 5]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 28 2012

CROSSREFS

Sequence in context: A027438 A204237 A153162 * A251736 A076520 A014249

Adjacent sequences:  A168196 A168197 A168198 * A168200 A168201 A168202

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Nov 20 2009

STATUS

approved

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Last modified August 23 13:45 EDT 2019. Contains 326227 sequences. (Running on oeis4.)