OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..445
FORMULA
a(n) = Sum_{k=0..n} A104984(n, k).
MATHEMATICA
PROG
(PARI) {a(n)=sum(k=0, n, if(k==n, 1, if(k==n-1, -n, -polcoeff((1-1/sum(i=0, n-k, i!*x^i))/x+O(x^(n-k)), n-k-1) )))}
(Sage)
@CachedFunction
def T(n, k):
if (k==n): return 1
elif (k==n-1): return -n
else: return -factorial(n-k) - sum( factorial(j)*T(n-k-j, 0) for j in (1..n-k-1) )
[sum(T(n, k) for k in (0..n)) for n in (0..30)] # G. C. Greubel, Jun 07 2021
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Apr 10 2005
STATUS
approved