%I M2381 #19 Oct 24 2023 20:46:02

%S 3,4,25,108,735,5248,40824,362000,3628185,39045888,478988081,

%T 6227101888,87146087625,1314459353088,20922788404479,355737629952000,

%U 6402373698206889,121479069952000000

%N Number of permutations of length n with spread 2.

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

%H R. L. Graham and D. H. Lehmer, <a href="https://doi.org/10.1017/S1446788700019339">On the Permanent of Schur's Matrix</a>, Jour. Australian Math. Soc. 21 no. 4 (series A) (1976), 487-497.

%K nonn

%O 3,1

%A _N. J. A. Sloane_

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