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A121897 a(n) = 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5). 3
1, 1, 1, 1, 1, 3, 11, 131, 17291, 298995971, 29799530324409601, 80728364323218860837749108564353, 49748616842002716055120167595193322161740083228987208037683201 (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 4*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, 4*a[n-1]*a[n-2]*a[n-3]*a[n-4] - a[n-5]];  Table[a[n], {n, 15}]

RecurrenceTable[{a[1]==a[2]==a[3]==a[4]==a[5]==1, a[n]==4a[n-1]a[n-2]a[n-3]a[n-4]-a[n-5]}, a, {n, 15}] (* Harvey P. Dale, Dec 16 2018 *)

PROG

(PARI) my(m=15, v=concat([1, 1, 1, 1, 1], vector(m-5))); for(n=6, m, v[n] = 4*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 4*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 4*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 4*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, A121910.

Sequence in context: A072878 A112957 A057205 * A067657 A063502 A329626

Adjacent sequences:  A121894 A121895 A121896 * A121898 A121899 A121900

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 June 6 10:43 EDT 2020. Contains 334842 sequences. (Running on oeis4.)