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A127021 Number of rhyme schemes (see reference for precise definition). 2
1, 11, 80, 491, 2777, 15120, 81371, 440947, 2441334, 13976885, 83547881, 525082654, 3483272777, 24413200487, 180517606216, 1404147099951, 11449330342717, 97521479081952, 864955731435983, 7966538662094103 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,2

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

Table of n, a(n) for n=4..23.

J. Riordan, Cached copy of paper

FORMULA

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

CROSSREFS

Cf. A005002, A005003.

Sequence in context: A227244 A026897 A021024 * A326243 A091098 A091115

Adjacent sequences:  A127018 A127019 A127020 * A127022 A127023 A127024

KEYWORD

nonn

AUTHOR

R. J. Mathar, Jul 15 2008

STATUS

approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)