A004206 Number of permutations of length n with spread 2.

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

Offset: 3

Author

N. J. A. Sloane

Keywords

• nonn

References

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

Links

• 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.

Extensions

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