OFFSET
1,2
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..60
Philippe Di Francesco, Twenty Vertex model and domino tilings of the Aztec triangle, arXiv:2102.02920 [math.CO], 2021.
Frederick Huang, The 20 Vertex Model and Related Domino Tilings, Ph. D. Dissertation, UC Berkeley, 2023. See p. 1.
FORMULA
a(n) ~ exp(1/48) * Pi^(1/4) * 2^(9*n^2/2 + n/2 + 1/3) / (sqrt(Gamma(1/4)) * A^(1/4) * n^(7/48) * 3^(9*n^2/4 + 3*n/4 - 1/24)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Feb 08 2021
MATHEMATICA
Table[2^(n*(n-1)/2) * Product[(4*j + 2)!/(n + 2*j + 1)!, {j, 0, n-1}], {n, 1, 15}] (* Vaclav Kotesovec, Feb 08 2021 *)
PROG
(PARI) a(n) = 2^(n*(n-1)/2)*prod(j=0, n-1, (4*j+2)!/(n+2*j+1)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Feb 08 2021
STATUS
approved