A018931 The number of permutations of n cards in which 2 is the first card hit and 3 the next hit after 2.

0, 1, 2, 12, 72, 480, 3600, 30240, 282240, 2903040, 32659200, 399168000, 5269017600, 74724249600, 1133317785600, 18307441152000, 313841848320000, 5690998849536000, 108840352997376000, 2189611807358976000, 46225138155356160000, 1021818843434188800000

Offset: 3

Author

N. J. A. Sloane

Keywords

• nonn

Comments

From the game of Mousetrap.

References

• Daniel J. Mundfrom, A problem in permutations: the game of "Mousetrap". European J. Combin. 15 (1994), no. 6, 555-560.

Links

• D. J. Mundfrom, A problem of permutations: the Game of "Mousetrap", Eur. J. Combinat. 15 (1994) 555-560, Table 1.

Crossrefs

Cf. A002468.

Formula

a(n) = A062119(n-3), n > 4. - R. J. Mathar, Oct 02 2008

Extensions

Offset changed to 3 and more precise definition provided by R. J. Mathar, Oct 02 2008