A009529 Sin(tanh(x)*tan(x))/2 = Sum a(n)*x^(4*n+2)/(4*n+2)!.

1, -4, -79664, -627244864, -10054978651904, -281464457981584384, -9106562752258155720704, 743620567656757236530855936, 627496952440053395297142177857536

Offset

0,2

Links

Table of n, a(n) for n=0..8.

Example

sin(tanh(x)*tan(x))/2 = (1/2)*x^2 - (1/180)*x^6 - (4979/226800)*x^10 - (9800701/1362160800)*x^14 - (39277260359/
25009272288000)*x^18 + ..., and (say) -(4979/226800)*10! = -79664 = a(2).

Mathematica

Sin[ Tanh[ x ]*Tan[ x ] ]/2 (* [ x^(4n+2) ] *)

Crossrefs

Cf. A012667.

Sequence in context: A257769 A370683 A066544 * A339450 A273231 A360760

Adjacent sequences: A009526 A009527 A009528 * A009530 A009531 A009532

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs Mar 1997

Edited by N. J. A. Sloane, Apr 02 2017

Status

approved