A004206 Number of permutations of length n with spread 2. (Formerly M2381)

3, 4, 25, 108, 735, 5248, 40824, 362000, 3628185, 39045888, 478988081, 6227101888, 87146087625, 1314459353088, 20922788404479, 355737629952000, 6402373698206889, 121479069952000000

Offset

3,1

References

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Table of n, a(n) for n=3..20.

R. L. Graham and D. H. Lehmer, On the Permanent of Schur's Matrix, Jour. Australian Math. Soc. 21 no. 4 (series A) (1976), 487-497.

Crossrefs

Sequence in context: A192346 A335739 A055348 * A302397 A151372 A258103

Adjacent sequences: A004203 A004204 A004205 * A004207 A004208 A004209

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 17 2007

Status

approved