A276130 a(0) = a(1) = a(2) = a(3) = a(4) = 1; for n>4, a(n) = ( a(n-1) +a(n-3) )*( a(n-2)+a(n-4) ) / a(n-5).

1, 1, 1, 1, 1, 4, 10, 55, 649, 38881, 6414706, 24978826228, 2913605221297249, 112139525368095766797655, 8403341152380185679389503620974065, 146904111947501701959735285821948223340424963459227

Offset

0,6

Links

Seiichi Manyama, Table of n, a(n) for n = 0..22

Formula

a(n) = (9-3*(-1)^n)/2*a(n-1)*a(n-3)-a(n-2)-a(n-4).

Prog

(PARI) a(n) = if (n<=4, 1, (9-3*(-1)^n)/2*a(n-1)*a(n-3)-a(n-2)-a(n-4)); \\ Michel Marcus, Aug 27 2016

Crossrefs

Cf. A006721.

Sequence in context: A197902 A276123 A096423 * A263044 A013589 A225543

Adjacent sequences: A276127 A276128 A276129 * A276131 A276132 A276133

Keyword

nonn

Author

Bruno Langlois, Aug 21 2016

Status

approved