A119601 a(n) = 4*Product_{i=1..2n-1} (3^i+1)^2.

4, 64, 5017600, 2008645953126400, 5124408580006984170864640000, 85495432669493277396354169745064287272960000, 9355246290649672947599943358541996936410690283965618585600000000, 6716146186611919497047421474121060203152077041964192052138083160878210999543398400000000, 31633930525439354064905560668985964653660262913501499819669450560971550674840773249412865611450669691043840000000000

Offset

0,1

Links

Table of n, a(n) for n=0..8.

R. Chapman et al., 2-modular lattices from ternary codes, J. Th. des Nombres de Bordeaux, 14 (2002), 73-85.

Mathematica

Table[4*Product[(3^i+1)^2, {i, 2n-1}], {n, 0, 8}] (* James C. McMahon, Sep 17 2024 *)

Prog

(PARI) a(n) = 4*prod(i=1, 2*n-1, (3^i+1)^2); \\ Michel Marcus, Oct 28 2015

Crossrefs

Sequence in context: A033635 A138835 A234608 * A058438 A171959 A041119

Adjacent sequences: A119598 A119599 A119600 * A119602 A119603 A119604

Keyword

nonn

Author

N. J. A. Sloane, Jun 04 2006

Status

approved