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A052870 A simple grammar. 1
1, 1, 2, 6, 15, 44, 128, 386, 1179, 3679, 11601, 37030, 119262, 387325, 1266647, 4168264, 13791565, 45856091, 153134306, 513403575, 1727395042, 5830866601, 19740613869, 67014421326, 228066659185, 777961702283, 2659398743509, 9109015516017, 31258117755635 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..28.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 841

MAPLE

spec := [S, {C=Sequence(Z, 1 <= card), S=PowerSet(B), B=Prod(C, S)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);

CROSSREFS

Sequence in context: A148439 A151515 A264746 * A293743 A001444 A293744

Adjacent sequences:  A052867 A052868 A052869 * A052871 A052872 A052873

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

EXTENSIONS

More terms from Alois P. Heinz, Mar 16 2016

STATUS

approved

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Last modified April 19 17:46 EDT 2021. Contains 343117 sequences. (Running on oeis4.)