The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A052135 Denominators of coefficients in function a(x) such that a(a(a(x))) = sin x. 3
 1, 18, 1080, 408240, 29393280, 215550720, 648499737600, 953294614272000, 2333665215737856000, 7183021534041120768000, 232066849561328517120000, 723095875143672151080960000, 74189636789740762700906496000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Also denominators of coefficients in function a(x) such that a(a(a(x))) = sinh x. REFERENCES W. C. Yang, Composition equations, preprint, 1999. LINKS MATHEMATICA n = 13; m = 2 n - 1 (* m = maximal degree *); a[x_] = Sum[c[k] x^k, {k, 1, m, 2}] ; coes = DeleteCases[ CoefficientList[Series[a @ a @ a @ x - Sin[x], {x, 0, m}], x] // Rest , 0]; Do[s[k] = Solve[coes[[1]] == 0] // First; coes = coes /. s[k] // Rest, {k, 1, n}] (CoefficientList[a[x] /. Flatten @ Array[s, n], x] // Denominator // Partition[#, 2] &)[[All, 2]] (* Jean-François Alcover, May 04 2011 *) CROSSREFS Cf. A052132, A052134. See also A048602, A048603, etc. Sequence in context: A301651 A159379 A323571 * A033518 A333006 A064564 Adjacent sequences:  A052132 A052133 A052134 * A052136 A052137 A052138 KEYWORD nonn,frac,easy,nice AUTHOR N. J. A. Sloane, Jan 22 2000 EXTENSIONS More terms from Vladeta Jovovic, Jul 16 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 2 14:48 EST 2021. Contains 349445 sequences. (Running on oeis4.)