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URL: https://oeis.org/A056048

⇱ A056048 - OEIS

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A056048
Number of 5-antichain covers of a labeled n-set.
2
0, 0, 0, 0, 6, 2116, 291966, 23312156, 1362515742, 65691305652, 2792020643502, 108871903828732, 3995501812110798, 140371634250355508, 4776934559777356158, 158783001150185585628, 5186356918189216064574, 167203226479257200020084, 5337930997910228958536334
OFFSET
0,5
REFERENCES
V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)
V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.
LINKS
K. S. Brown, Dedekind's problem
Eric Weisstein's World of Mathematics, Antichain covers
FORMULA
a(n) = (1/5!) * (31^n - 20*23^n + 60*19^n + 20*17^n + 10*16^n - 110*15^n - 120*14^n + 150*13^n + 120*12^n - 240*11^n + 20*10^n + 240*9^n + 40*8^n - 205*7^n + 60*6^n - 210*5^n + 210*4^n + 50*3^n - 100*2^n + 24).
MATHEMATICA
Table[(1/5!)*(31^n - 20*23^n + 60*19^n + 20*17^n + 10*16^n - 110*15^n - 120*14^n + 150*13^n + 120*12^n - 240*11^n + 20*10^n + 240*9^n + 40*8^n - 205*7^n + 60*6^n - 210*5^n + 210*4^n + 50*3^n - 100*2^n + 24), {n, 0, 25}] (* G. C. Greubel, Oct 07 2017 *)
PROG
(PARI) for(n=0, 25, print1((31^n - 20*23^n + 60*19^n + 20*17^n + 10*16^n - 110*15^n - 120*14^n + 150*13^n + 120*12^n - 240*11^n + 20*10^n + 240*9^n + 40*8^n - 205*7^n + 60*6^n - 210*5^n + 210*4^n + 50*3^n - 100*2^n + 24)/120, ", ")) \\ G. C. Greubel, Oct 07 2017
(Magma) [(31^n - 20*23^n + 60*19^n + 20*17^n + 10*16^n - 110*15^n - 120*14^n + 150*13^n + 120*12^n - 240*11^n + 20*10^n + 240*9^n + 40*8^n - 205*7^n + 60*6^n - 210*5^n + 210*4^n + 50*3^n - 100*2^n + 24)/120: n in [0..25]]; // G. C. Greubel, Oct 07 2017
CROSSREFS
Cf. A051113.
Sequence in context: A226461 A172943 A182789 * A051113 A067174 A153300
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Goran Kilibarda, Zoran Maksimovic, Jul 25 2000
STATUS
approved