A120346 - OEIS

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A120346

Number of permutations avoiding 3142, 25314, 246135 and 362514.

1, 2, 6, 23, 102, 492, 2498, 13130, 70800, 389446, 2176802, 12328552, 70597568, 408061604, 2377643974, 13950607135, 82355028006, 488797440712, 2915087969496, 17459865132260, 104981190319396, 633438776314456

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OFFSET

1,2

COMMENTS

These permutations are the wreath closure of 1, 12, 21 and 2413.

LINKS

Table of n, a(n) for n=1..22.

R. Brignall, S. Huczynska and V. Vatter, Simple permutations and algebraic generating functions, arXiv:math.CO/0608391.

FORMULA

G.f. satisfies f^5+f^4+f^2+(x-1)f+x=0.

EXAMPLE

a(4)=23 because all permutations of length 4 except 3142 lies in this set.

CROSSREFS

Sequence in context: A231444 A248900 A376395 * A050389 A098746 A245389

Adjacent sequences: A120343 A120344 A120345 * A120347 A120348 A120349

KEYWORD

nonn

AUTHOR

Vincent Vatter, Aug 16 2006

STATUS

approved