A116801 Number of permutations of length n which avoid the patterns 1234, 1432, 2413.

1, 2, 6, 21, 71, 229, 726, 2299, 7296, 23180, 73648, 233935, 742924, 2359143, 7491146, 23786672, 75528789, 239820410, 761475614, 2417816525, 7676955811, 24375507011, 77395827653, 245742882637, 780268393400, 2477461176578

Offset

1,2

Links

Table of n, a(n) for n=1..26.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 (2017), Table 2 No 37.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (7,-18,24,-19,7,-4,1,-1).

Formula

G.f.: A(x) = -{(x^7-x^6+3x^5-3x^4+9x^3-10x^2+5x-1)x}/{x^8-x^7+4x^6-7x^5+19x^4-24x^3+18x^2-7x+1}

Crossrefs

Sequence in context: A116807 A294702 A116785 * A148486 A294753 A294754

Adjacent sequences: A116798 A116799 A116800 * A116802 A116803 A116804

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved