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A009617
Expansion of e.g.f. sinh(tanh(x)*tan(x))/2 in odd powers of x^2.
0
1, 116, 202576, 1557978176, 34206677698816, 1706222428480541696, 167325183704890858786816, 29168516299952885066683006976, 8389219957754997383106354075467776, 3758865858584530123647466441487099887616, 2506919694437630172543194103107513029881757696
OFFSET
0,2
LINKS
EXAMPLE
x^2/2! + 116*x^6/6! + 202576*x^10/10! + 1557978176*x^14/14! ...
MATHEMATICA
Sinh[ Tanh[ x ]*Tan[ x ] ]/2 (* [ x^(4n+2) ] *)
PROG
(PARI) seq(n)={my(A=O(x^(4*n+2))); Vec(substpol(serlaplace( sinh(tanh(x + A)*tan(x + A))/2 )/x^2, x^4, x))} \\ Andrew Howroyd, Jan 12 2025
CROSSREFS
Cf. A012671.
Sequence in context: A296360 A035814 A284377 * A201728 A009687 A373582
KEYWORD
nonn,changed
AUTHOR
EXTENSIONS
Extended and signs tested 03/97.
a(9) onwards from Andrew Howroyd, Jan 12 2025
STATUS
approved