0,4

spec := [ S, {N=Union(Z, S, P, Q), S=Set(Union(Z, P, Q), card>=2), P=Set(Union(Z, S, Q), card>=2), Q=Set(Union(Z, S, P), card>=2)} ]; [seq(combstruct[count](spec, size=n), n=0..40)]; # N=A058540, S=A058371

spec:=[S, {S=Set(Union(Z, S, S), card>=2)}]; [seq(combstruct[count](spec, size=n), n=0..25)]; - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jun 25 2007

Cf. A058575.

Sequence in context: A002001 A113956 A103943 this_sequence A060113 A134589 A037758

Adjacent sequences: A058368 A058369 A058370 this_sequence A058372 A058373 A058374

nonn

njas, Dec 26 2000