A245384 a(n) = (1 + a(n-1)) * a(n-2) * a(n-3) with a(1) = 1, a(2) = 2, a(3) = 3.

1, 2, 3, 8, 54, 1320, 570672, 40677571440, 30641887385179424640, 711307017047678652146384291462042880, 886599784992546696966754646294076268713472764725575212247451289600

Offset

1,2

Links

Michael Somos, Table of n, a(n) for n = 1..11

Formula

a(n) = A245366(n) - 1 for n>0.

a(n) = A245283(n+3) / A245283(n+2) for n>0.

Mathematica

a[ n_] := If[ n < 4, Max[1, n], a[n] = (1 + a[n-1]) a[n-2] a[n-3]];

Prog

(PARI) {a(n) = if( n<4, max(1, n), (1 + a(n-1)) * a(n-2) * a(n-3))};
(Magma) I:=[1, 2, 3]; [n le 3 select I[n] else (1 + Self(n-1))*Self(n-2)* Self(n-3): n in [1..15]]; // G. C. Greubel, Aug 05 2018

Crossrefs

Cf. A245283, A245366.

Sequence in context: A001686 A013205 A340486 * A292893 A356902 A042365

Adjacent sequences: A245381 A245382 A245383 * A245385 A245386 A245387

Keyword

nonn

Author

Michael Somos, Aug 21 2014

Status

approved