This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A023422 Generalized Catalan Numbers. 5
 1, 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 129, 261, 530, 1080, 2208, 4528, 9313, 19207, 39714, 82314, 170996, 355976, 742545, 1551817, 3248823, 6812947, 14309557, 30099645, 63402315 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..2926 A. Goupil, M.-E. Pellerin and J. de Wouters d'oplinter, Snake Polyominoes, arXiv preprint arXiv:1307.8432, 2013. (Gives a g.f.) MATHEMATICA a[0]=1; a[n_]:= a[n]=a[n-1] + Sum[a[k]*a[n-2-k], {k, 4, n-2}]; Table[a[n], {n, 0, 30}] (* modified by G. C. Greubel, Jan 01 2018 *) PROG (PARI) {a(n) = if(n==0, 1, a(n-1) + sum(k=4, n-2, a(k)*a(n-k-2)))}; for(n=0, 30, print1(a(n), ", ")) \\ G. C. Greubel, Jan 01 2018 CROSSREFS Cf. A000108, A001006, A004148, A004149, A023421, A023423. Fifth row of A064645. Sequence in context: A278995 A117302 A265407 * A084638 A157021 A210543 Adjacent sequences:  A023419 A023420 A023421 * A023423 A023424 A023425 KEYWORD nonn,easy AUTHOR 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 January 19 03:18 EST 2019. Contains 319282 sequences. (Running on oeis4.)