OFFSET
0,3
LINKS
A. M. Goyt, Avoidance of partitions of a 3-element set, arXiv:math/0603481 [math.CO], 2006-2007
FORMULA
a(0)=1, a(1)=1, a(n) = 1 + a(n-1) + Sum_{k=1..n-2} binomial(n-2, k)*a(n-k-2).
The e.g.f. satisfies the differential equation y'' = y' + y(e^x-1) + e^x.
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, May 08 2007
STATUS
approved