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

3,3

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

Table of n, a(n) for n=3..24.

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

Formula

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

Crossrefs

Cf. A002468.

Sequence in context: A322276 A279154 A167747 * A062119 A181966 A052556

Adjacent sequences: A018928 A018929 A018930 * A018932 A018933 A018934

Keyword

nonn

Author

N. J. A. Sloane

Extensions

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

Status

approved