OFFSET
0,2
COMMENTS
a(n) is the largest integer smaller than the (reciprocal) proportion of partitions of the set {1,..,2n} that refine the partition {1,..,n|n+1,..,2*n}.
MATHEMATICA
Table[Floor[BellB[2*n]/BellB[n]^2], {n, 0, 30}] (* Vaclav Kotesovec, Jul 23 2021 *)
PROG
(GAP) QuoInt(Bell(2*n), Bell(n)^2)
CROSSREFS
KEYWORD
nonn
AUTHOR
Nick Loughlin, May 01 2014
STATUS
approved