A086502 - OEIS

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A086502

Number of ordered pairs (a,b) of elements of the symmetric group S_n such that the pair a,b generates a proper subgroup of S_n.

0

0, 1, 18, 360, 7560, 289440, 9828000, 631169280, 46449002880, 4526271187200, 524461965350400, 74044329341875200, 12211524764030592000

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..13.

FORMULA

a(n) = n!^2 - A071605(n).

CROSSREFS

Sequence in context: A366684 A182609 A320764 * A259459 A099276 A221348

Adjacent sequences: A086499 A086500 A086501 * A086503 A086504 A086505

KEYWORD

nonn

AUTHOR

Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 09 2003

EXTENSIONS

a(10)-(13) from Stephen A. Silver, Feb 21 2013

STATUS

approved