|
| |
|
|
A086855
|
|
Number of permutations of length n with exactly 4 rising or falling successions.
|
|
2
| |
|
|
0, 0, 0, 0, 0, 2, 22, 226, 2198, 22120, 236968, 2732268, 33940644, 453148422, 6480322210, 98907371822, 1605581578202, 27631315113916, 502618772515748, 9637245372790760, 194291040277517688, 4109014039030693578, 90968013940830446574, 2104072961763468757082
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,6
|
|
|
COMMENTS
| Permutations of 12...n such that exactly 4 of the following occur: 12, 23, ..., (n-1)n, 21, 32, ..., n(n-1).
|
|
|
REFERENCES
| F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 263.
J. Riordan, A recurrence for permutations without rising or falling successions. Ann. Math. Statist. 36 (1965), 708-710.
|
|
|
FORMULA
| Coefficient of t^4 in S[n](t) defined in A002464.
|
|
|
CROSSREFS
| Cf. A002464, A000130, A000349, A001267, A086852, A086853. A diagonal of A001100.
Twice A001268.
Sequence in context: A137109 A002276 A112893 * A089182 A138140 A151617
Adjacent sequences: A086852 A086853 A086854 * A086856 A086857 A086858
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Aug 19 2003
|
| |
|
|
