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A121910 a(n) = 3*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5), with a(0)=...=a(4)=1. 2
1, 1, 1, 1, 1, 2, 5, 29, 869, 756029, 285790302433, 16335219393063437264866, 9201358366190200404401435237110861938769705 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..17

MAPLE

a:= proc(n) option remember;

      if n<6 then 1

    else 3*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5)

      fi;

    end:

seq(a(n), n=1..15); # G. C. Greubel, Oct 07 2019

MATHEMATICA

a[n_]:= a[n]= If[n<6, 1, 3*a[n-1]*a[n-2]*a[n-3]*a[n-4] - a[n-5]]; Table[a[n], {n, 15}] (* modified by G. C. Greubel, Oct 07 2019 *)

PROG

(PARI) my(m=15, v=concat([1, 1, 1, 1, 1], vector(m-5))); for(n=6, m, v[n] = 3*v[n-1] *v[n-2]*v[n-3]*v[n-4] - v[n-5]); v \\ G. C. Greubel, Oct 07 2019

(MAGMA) [n lt 6 select 1 else 3*Self(n-1)*Self(n-2)*Self(n-3)*Self(n-4) - Self(n-5): n in [1..15]]; // G. C. Greubel, Oct 07 2019

(Sage)

def a(n):

    if (n<6): return 1

    else: return 3*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5)

[a(n) for n in (1..15)] # G. C. Greubel, Oct 07 2019

(GAP)

a:= function(n)

    if n<6 then return 1;

    else return 3*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5);

    fi;

  end;

List([1..15], n-> a(n) ); # G. C. Greubel, Oct 05 2019

CROSSREFS

Cf. A072879, A121897.

Sequence in context: A098717 A059784 A000283 * A073833 A229918 A179554

Adjacent sequences:  A121907 A121908 A121909 * A121911 A121912 A121913

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Sep 09 2006

EXTENSIONS

Edited by N. J. A. Sloane, Sep 15 2006

STATUS

approved

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Last modified August 11 15:12 EDT 2020. Contains 336428 sequences. (Running on oeis4.)