%I
%S 1,1,2,6,24,120,720,5040,40320,362880,2903040,32659200,333849600,
%T 4470681600,55244851200,855496857600,12362073292800,216999220838400,
%U 3584572069478400,70276861528473600,1305169212624076800,28251875803447296000,582386191297118208000
%N Number of permutations of 1..n with no adjacent pair summing to n + 9.
%C If a(n,k) is the number of permutations of 1..n with no adjacent pair summing to n+k, then a(n,k) = a(n,k+1) for n+k even.
%F k = 9; m = max(0, floor((nk+1)/2)); a(n,k) = Sum_{j=0..m} (2)^j * binomial(m,j)*(nj)!.
%K nonn
%O 0,3
%A _R. H. Hardin_, Feb 26 2010
%E Comment proved by William Keith, formula from _Max Alekseyev_, on the Sequence Fans Mailing List
%E More terms from _Alois P. Heinz_, Jan 09 2017
