OFFSET
0,2
COMMENTS
Table A322190 gives the coefficients of x^n*y^k/(n!*k!) in (cosh(x)*cosh(y) + sinh(x) + sinh(y)) / (1 - sinh(x)*sinh(y)).
LINKS
Paul D. Hanna, Table of n, a(n) for n = 0..150
FORMULA
a(n) ~ Pi * n^(n+1) / (2^(n - 3/4) * exp(n) * (log(1+sqrt(2)))^(n + 3/2)). - Vaclav Kotesovec, Dec 30 2018
MATHEMATICA
nmax = 30;
t[n_, k_] := SeriesCoefficient[(Cosh[x] Cosh[y] + Sinh[x] + Sinh[y])/(1 - Sinh[x] Sinh[y]), {x, 0, n}, {y, 0, k}] n! k!;
a[n_] := Sum[t[n - k, k], {k, 0, n}];
Table[a[n], {n, 0, nmax}] (* Jean-François Alcover, Dec 29 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 20 2018
STATUS
approved