OFFSET
0,3
LINKS
T.-X. He, A symbolic operator approach to power series transformation-expansion formulas, JIS 11 (2008) 08.2.7
FORMULA
a(n) = Sum_{k=0..floor(n/2)} (((n-k)!/k!)*sum{i=0..n-2k} C(n-2k-1,i)/(n-2k-i)!).
PROG
(PARI) a(n) = sum(k=0, n\2, ((n-k)!/k!)*sum(i=0, n-2*k, binomial(n-2*k-1, i)/(n-2*k-i)!)); \\ Michel Marcus, Sep 10 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Apr 26 2007
STATUS
approved