A001054 a(n) = a(n-1)*a(n-2) - 1.

0, 1, -1, -2, 1, -3, -4, 11, -45, -496, 22319, -11070225, -247076351776, 2735190806339469599, -675800965841611881515781657825, -1848444588685310753420392017318175868503407962176

Offset

0,4

Links

John Cerkan, Table of n, a(n) for n = 0..21

Maple

a:= proc (n) option remember;
if n<2 then n
else a(n-1)*a(n-2) - 1
end if
end proc;
seq(a(n), n = 0..15); # G. C. Greubel, Sep 20 2019

Mathematica

RecurrenceTable[{a[0]==0, a[1]==1, a[n]==a[n-1]*a[n-2] -1}, a, {n, 0, 15}] (* G. C. Greubel, Sep 20 2019 *)

Prog

(PARI) m=15; v=concat([0, 1], vector(m-2)); for(n=3, m, v[n]=v[n-1]*v[n-2] -1 ); v \\ G. C. Greubel, Sep 20 2019
(Magma) I:=[0, 1]; [n le 2 select I[n] else Self(n-1)*Self(n-2) -1: n in [1..15]]; // G. C. Greubel, Sep 20 2019
(Sage)
def a(n):
    if (n<2): return n
    else: return a(n-1)*a(n-2) -1
[a(n) for n in (0..15)] # G. C. Greubel, Sep 20 2019
(GAP) a:=[0, 1];; for n in [3..15] do a[n]:=a[n-1]*a[n-2] -1; od; a; # G. C. Greubel, Sep 20 2019

Crossrefs

Sequence in context: A166476 A052950 A086851 * A375364 A218209 A141487

Adjacent sequences: A001051 A001052 A001053 * A001055 A001056 A001057

Keyword

easy,sign

Author

R. K. Guy

Status

approved