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A135055
Pentanacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) + a(n-5) for n>4 and with a(0)=-2, a(1)=-1, a(2)=0, a(3)=1, a(4)=2.
3
-2, -1, 0, 1, 2, 0, 2, 5, 10, 19, 36, 72, 142, 279, 548, 1077, 2118, 4164, 8186, 16093, 31638, 62199, 122280, 240396, 472606, 929119, 1826600, 3591001, 7059722, 13879048, 27285490, 53641861, 105457122, 207323243, 407586764, 801294480, 1575303470, 3096965079, 6088473036, 11969622829
OFFSET
0,1
LINKS
Piezas, Tito III and Weisstein, Eric W., Pentanacci Number
FORMULA
From R. J. Mathar, Nov 18 2007: (Start)
G.f.: (1-2*x)*(x+1)*(2*x^2+x+2)/(-1+x+x^2+x^3+x^4+x^5).
a(n) = -2*A001591(n+4) + A001591(n+3) + 3*A001591(n+2) + 4*A001591(n+1) + 4*A001591(n). (End)
MATHEMATICA
a[n_] := a[n] = a[n - 1] + a[n - 2] + a[n - 3] + a[n - 4] + a[n - 5]; a[0] = -2; a[1] = -1; a[2] = 0; a[3] = 1; a[4] = 2; Table[a[n], {n, 0, 50}] (* Artur Jasinski, Nov 15 2007 *)
LinearRecurrence[{1, 1, 1, 1, 1}, {-2, -1, 0, 1, 2}, 50] (* G. C. Greubel, Sep 21 2016 *)
PROG
(Magma) I:=[-2, -1, 0, 1, 2]; [n le 5 select I[n] else Self(n-1)+Self(n-2)+Self(n-3)+Self(n-4)+Self(n-5): n in [1..40]]; // Vincenzo Librandi, Sep 22 2016
CROSSREFS
Sequence in context: A108964 A036581 A369462 * A265433 A298247 A035148
KEYWORD
sign,easy
AUTHOR
Artur Jasinski, Nov 15 2007
STATUS
approved