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A217675

Number of permutations in S_n containing an increasing subsequence of length 8.

1, 65, 2603, 83923, 2410291, 64864819, 1683724308, 42918747000, 1086997811325, 27571922195325, 704311698875426, 18189847735254134, 476311846323448840, 12672229166094171240, 343069245941729668380, 9461927811882316662636, 266091066751920438364275

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OFFSET

8,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 8..200

FORMULA

a(n) = A214152(n,8) = A000142(n)-A072131(n) = A000142(n)-A214015(n,7).

EXAMPLE

a(8) = 1: 12345678.

MAPLE

b:= proc(n) option remember; `if`(n<8, n!, ((-343035+429858*n

+238440*n^3+38958*n^4+634756*n^2+2940*n^5+84*n^6)*b(n-1)

-(1974*n^4+36336*n^3+213240*n^2+407840*n+82425)*(n-1)^2*b(n-2)

+2*(49875+42646*n+6458*n^2)*(n-1)^2*(n-2)^2*b(n-3)

-11025*(n-1)^2*(n-2)^2*(n-3)^2*b(n-4))/ ((n+6)^2*(n+10)^2*(n+12)^2))

end:

a:= n-> n! -b(n):

seq(a(n), n=8..25);

CROSSREFS

Cf. A000142, A072131, A214015, A214152.

Sequence in context: A300168 A004354 A016111 * A237858 A383754 A075474

Adjacent sequences: A217672 A217673 A217674 * A217676 A217677 A217678

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 10 2012

STATUS

approved

URL: https://oeis.org/A217675

⇱ A217675 - OEIS