login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A063021 Reversion of y - y^2 - y^5. 0
0, 1, 1, 2, 5, 15, 49, 168, 594, 2150, 7931, 29718, 112814, 432957, 1677050, 6547856, 25742454, 101819100, 404885630, 1617725010, 6491294600, 26147434885, 105691660110, 428578242900, 1742925259725, 7106942278683 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..25.

Vladimir Kruchinin, The method for obtaining expressions for coefficients of reverse generating functions, arXiv:1211.3244 [math.CO], 2012.

Index entries for reversions of series

FORMULA

a(n) = sum(j=0..(n-1)/3, C(n-1-3*j,j)*C(2*n-3*j-2,n-1))/n, n>0, a(0)=0. - Vladimir Kruchinin, May 24 2011

MATHEMATICA

CoefficientList[InverseSeries[Series[y - y^2 - y^5, {y, 0, 30}], x], x]

PROG

(Maxima) a(n):=sum(binomial(n-1-3*j, j)*binomial(2*n-3*j-2, n-1), j, 0, (n-1)/3)/n; \\ Vladimir Kruchinin, May 24 2011

(PARI) Vec(serreverse(x-x^2-x^5+O(x^66))) /* Joerg Arndt, May 24 2011 */

CROSSREFS

Sequence in context: A149935 A149936 A189176 * A301832 A272460 A149937

Adjacent sequences:  A063018 A063019 A063020 * A063022 A063023 A063024

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard, Jul 05 2001

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 8 12:31 EST 2019. Contains 329864 sequences. (Running on oeis4.)