OFFSET
1,1
LINKS
A. R. Krauter, Uber die Permanente gewisser Matrizen und damit zusammenhangender..., Sem. Loth. Combinat. B11B (1984) 82-94, eq. (3.12)
FORMULA
a(n) = Sum_{k=0..n} (-2)^k*2*n*binomial(2*n-k,k)*(n-k)!/(2*n-k).
a(n) ~ exp(-4) * n!. - Vaclav Kotesovec, Dec 17 2015
Conjecture: (-n+2)*a(n) +(n^2-4*n+6)*a(n-1) +2*(n^2-2*n+3)*a(n-2) +8*(n-1)*a(n-3) = 0. - R. J. Mathar, Jul 20 2016
Conjecture: a(n) -n*a(n-1) -8*a(n-2) +4*(n-4)*a(n-3) +16*a(n-4) = 0. - R. J. Mathar, Jul 20 2016
MAPLE
A195422 := proc(n)
local k;
add((-2)^k*2*n*binomial(2*n-k, k)*(n-k)!/(2*n-k), k=0..n) ;
end proc: # R. J. Mathar, Jul 20 2016
MATHEMATICA
Table[Sum[(-2)^k*2*n*Binomial[2*n - k, k]*(n - k)!/(2*n - k), {k, 0, n}], {n, 1, 20}] (* Vaclav Kotesovec, Dec 17 2015 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
R. J. Mathar, Sep 18 2011
STATUS
approved