A048606 Numerators of coefficients in function a(x) such that a(a(x)) = sinh(x).

1, 1, -1, 53, -23, 92713, -742031, -594673187, 329366540401, -104491760828591, 1508486324285153, 582710832978168221, -1084662989735717135537, 431265609837882130202597, 784759327625761394688977441

Offset

0,4

Comments

A recursion exists for coefficients, but is too complicated to use without a computer algebra system.

References

W. C. Yang, Polynomials are essentially integer partitions, preprint, 1999

W. C. Yang, Composition equations, preprint, 1999

Links

Table of n, a(n) for n=0..14.

W. C. Yang, Derivatives are essentially integer partitions, Discrete Math., 222 (2000), 235-245.

Example

x + x^3/12 - x^5/160 + ...

Crossrefs

Cf. A048603. Apart from signs, the same sequence as A048602.

Sequence in context: A298633 A298710 A048602 * A033373 A289237 A319904

Adjacent sequences: A048603 A048604 A048605 * A048607 A048608 A048609

Keyword

frac,sign,nice

Author

Winston C. Yang (yang(AT)math.wisc.edu)

Status

approved