A127021 Number of rhyme schemes (see reference for precise definition).

1, 11, 80, 491, 2777, 15120, 81371, 440947, 2441334, 13976885, 83547881, 525082654, 3483272777, 24413200487, 180517606216, 1404147099951, 11449330342717, 97521479081952, 864955731435983, 7966538662094103

Offset: 4

Author

R. J. Mathar, Jul 15 2008

Keywords

• nonn

References

• J. Riordan, A budget of rhyme scheme counts, pp. 455 - 465 of Second International Conference on Combinatorial Mathematics, New York, April 4-7, 1978. Edited by Allan Gewirtz and Louis V. Quintas. Annals New York Academy of Sciences, 319, 1979.

Links

• J. Riordan, Cached copy of paper

Crossrefs

Cf. A005002, A005003.

Formula

a(k)=1. a(n)=k*a(n-1)+A000110(n-1)-A102661(n-1,k-2), k=4.