A319948 a(n) = Product_{i=1..n} floor(3*i/2).

1, 3, 12, 72, 504, 4536, 45360, 544320, 7076160, 106142400, 1698278400, 30569011200, 580811212800, 12197035468800, 268334780313600, 6440034727526400, 161000868188160000, 4347023441080320000, 121716656350248960000, 3651499690507468800000

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Formula

a(n) ~ (3/2)^n * n! * 2^(1/6) * sqrt(Pi) / (Gamma(1/3) * n^(1/6)).

Recurrence: 4*a(n) - 6*a(n-1) - 3*(n - 1)*(3*n - 4)*a(n-2) = 0, with n >= 3. - Bruno Berselli, Oct 03 2018

Mathematica

Table[Product[Floor[i*3/2], {i, 1, n}], {n, 1, 20}]
RecurrenceTable[{4 a[n] - 6 a[n - 1] - 3 (n - 1) (3 n - 4) a[n - 2] == 0, a[1] == 1, a[2] == 3}, a, {n, 1, 20}] (* Bruno Berselli, Oct 03 2018 *)

Crossrefs

Cf. A010786, A180736, A275062, A319949, A319950, A317980.

Sequence in context: A228386 A175836 A293138 * A020530 A337061 A147998

Adjacent sequences: A319945 A319946 A319947 * A319949 A319950 A319951

Keyword

nonn

Author

Vaclav Kotesovec, Oct 02 2018

Status

approved