The OEIS is supported by the many generous donors to the OEIS 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 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A127053 Expansion of 1/(1+9*x*c(x)), where c(x) = g.f. for Catalan numbers A000108. 7
 1, -9, 72, -585, 4734, -38358, 310662, -2516481, 20383110, -165104478, 1337341896, -10832484474, 87743071332, -710719065000, 5756823757890, -46630274845905, 377705217526470, -3059412293786310, 24781239462988800, -200728040080084110, 1625897123058144420 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Hankel transform is (-9)^n. LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 FORMULA a(n) = Sum_{k=0..n} A039599(n,k)*(-10)^k. G.f.: 2/(11 - 9*sqrt(1-4*x)). - G. C. Greubel, May 28 2019 MAPLE c:=(1-sqrt(1-4*x))/2/x: ser:=series(1/(1+9*x*c), x=0, 24): seq(coeff(ser, x, n), n=0..21); # Emeric Deutsch, Mar 23 2007 MATHEMATICA CoefficientList[Series[2/(11-9*Sqrt[1-4*x]), {x, 0, 30}], x] (* G. C. Greubel, May 28 2019 *) PROG (PARI) my(x='x+O('x^30)); Vec(2/(11-9*sqrt(1-4*x))) \\ G. C. Greubel, May 28 2019 (Magma) R:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( 2/(11-9*Sqrt(1-4*x)) )); // G. C. Greubel, May 28 2019 (Sage) (2/(11-9*sqrt(1-4*x))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 28 2019 CROSSREFS Cf. A000108, A039599. Sequence in context: A003951 A252702 A033135 * A001809 A006135 A180836 Adjacent sequences: A127050 A127051 A127052 * A127054 A127055 A127056 KEYWORD sign AUTHOR Philippe Deléham, Mar 21 2007 EXTENSIONS More terms from Emeric Deutsch, Mar 23 2007 STATUS approved

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

Last modified December 6 16:13 EST 2023. Contains 367612 sequences. (Running on oeis4.)