OFFSET
1,2
COMMENTS
Main diagonal of array in A212796.
LINKS
Germain Kreweras, Complexité et circuits Eulériens dans les sommes tensorielles de graphes, J. Combin. Theory, B 24 (1978), 202-212. See p. 210, Para. 4.
Eric Weisstein's World of Mathematics, Spanning Tree
Eric Weisstein's World of Mathematics, Torus Grid Graph
FORMULA
a(n) ~ Gamma(1/4)^4 * exp(4*G*n^2/Pi) / (16 * Pi^3), where G is Catalan's constant A006752. - Vaclav Kotesovec, Feb 14 2021
MATHEMATICA
Table[n^2 * Product[4*Sin[j*Pi/n]^2 + 4*Sin[k*Pi/n]^2, {k, 1, n-1}, {j, 1, n-1}], {n, 1, 12}] // Round (* Vaclav Kotesovec, Feb 14 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, May 27 2012
EXTENSIONS
More terms from Eric W. Weisstein, May 10 2017
STATUS
approved