OFFSET
1,1
COMMENTS
Recurrence would also extend to an a(0) if the definition were made to exclude the identity permutation.
LINKS
R. H. Hardin, Table of n, a(n) for n=1..32
FORMULA
Empirical: a(n)=20*a(n-1)-180*a(n-2)+964*a(n-3)-3422*a(n-4)+8484*a(n-5)-15068*a(n-6)+19324*a(n-7)-17769*a(n-8)+11432*a(n-9)-4888*a(n-10)+1248*a(n-11)-144*a(n-12) ; G.f.: -x*(-7736 +120061*x -837322*x^2 +3467912*x^3 -9484876*x^4 +17996064*x^5 -24175460*x^6 +22995433*x^7 -15176808*x^8 +6618712*x^9 -1716576*x^10 +200592*x^11) / ( (-1+3*x)^2*(2*x-1)^4*(x-1)^6 ).
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, g.f. from R. J. Mathar in the Sequence Fans Mailing List, Jul 19 2010
STATUS
approved