OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..62
FORMULA
a(n) ~ 2^(1/4)*(1 + sqrt(2)*(1 + (-1)^n)/2) * exp(2*G*n^2/Pi), where G is Catalan's constant A006752. - Vaclav Kotesovec, Feb 14 2021
If n is odd, a(n) = 2*A341478(n). - Seiichi Manyama, Feb 19 2021
MATHEMATICA
Table[Sqrt[Product[4*Sin[(2*j - 1)*Pi/(2*n)]^2 + 4*Sin[(2*k - 1)*Pi/n]^2, {k, 1, n}, {j, 1, n}]], {n, 0, 20}] // Round (* Vaclav Kotesovec, Feb 14 2021 *)
PROG
(PARI) default(realprecision, 120);
a(n) = round(sqrt(prod(j=1, n, prod(k=1, n, 4*sin((2*j-1)*Pi/(2*n))^2+4*sin((2*k-1)*Pi/n)^2))));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 13 2021
STATUS
approved