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 A022321 a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 7. 1
 1, 7, 9, 17, 27, 45, 73, 119, 193, 313, 507, 821, 1329, 2151, 3481, 5633, 9115, 14749, 23865, 38615, 62481, 101097, 163579, 264677, 428257, 692935, 1121193, 1814129, 2935323, 4749453, 7684777, 12434231 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (2,0,-1) FORMULA From R. J. Mathar, Apr 07 2011: (Start) G.f.: (1+5*x-5*x^2)/((1-x)*(1-x-x^2)). a(n) = 2*A000285(n) - 1. (End) a(n) = 2*F(n+2) + 4*F(n) - 1, where F = A000045. - G. C. Greubel, Aug 25 2017 MATHEMATICA a[0]=1; a[1]=7; a[n_]:=a[n]=a[n-1]+a[n-2]+1; Table[a[n], {n, 0, 40}] (* Harvey P. Dale, Jan 23 2011 *) PROG (PARI) x='x+O('x^50); Vec((1+5*x-5*x^2)/((1-x)*(1-x-x^2))) \\ G. C. Greubel, Aug 25 2017 CROSSREFS Sequence in context: A250292 A140364 A366526 * A194830 A183344 A255830 Adjacent sequences: A022318 A022319 A022320 * A022322 A022323 A022324 KEYWORD nonn AUTHOR N. J. A. Sloane STATUS approved

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Last modified December 5 23:11 EST 2023. Contains 367594 sequences. (Running on oeis4.)