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A052869
A simple grammar.
0
0, 1, 2, 4, 11, 29, 88, 271, 876, 2880, 9699, 33106, 114575, 400547, 1413333, 5025026, 17987892, 64769123, 234438337, 852519108, 3113091384, 11410682109, 41967420293, 154832147286, 572853387928, 2124996514900, 7901625442544, 29446874224295, 109965454516498
OFFSET
0,3
MAPLE
spec := [S, {C=Prod(Z, B), B=PowerSet(S), S=Set(C, 1<= card)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
CROSSREFS
Sequence in context: A148143 A148144 A148145 * A316768 A052831 A339834
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
More terms from Sean A. Irvine, Dec 01 2021
STATUS
approved