OFFSET
0,6
FORMULA
a(n) = |A104203(n)|.
E.g.f.: sn(x, 1/2) / cd(x, 1/2).
E.g.f. A(x) satisfies A(x)^2 = sinh(2 * Integral A(x) dx). - Michael Somos, Jun 17 2017
EXAMPLE
G.f. = x + 12*x^5 + 3024*x^9 + 4390848*x^13 + 21224560896*x^17 + ...
MATHEMATICA
a[ n_] := If[ n<0, 0, n! SeriesCoefficient[ JacobiSN[x, 1/2] / JacobiCD[x, 1/2], {x, 0, n}]];
PROG
(PARI) {a(n) = if( n<0, 0, n! * polcoeff( serreverse( intformal( (1 + x^4 + x * O(x^n))^(-1/2))), n))};
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, May 09 2014
STATUS
approved