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 A056047 Number of 4-antichain covers of a labeled n-set. 2
 0, 0, 0, 0, 25, 1895, 70370, 1868650, 41062035, 802349205, 14514339340, 249104207000, 4120588431245, 66392465654515, 1049608974433110, 16365222591176550, 252584307401055655, 3869412829938587825, 58950765174112191680, 894469325684769169300, 13531152125348360663265 (list; graph; refs; listen; history; text; internal format)
 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 G. C. Greubel, Table of n, a(n) for n = 0..845 K. S. Brown, Dedekind's problem Eric Weisstein's World of Mathematics, Antichain covers FORMULA a(n) = (1/4!)*(15^n - 12*11^n + 24*9^n + 4*8^n - 18*7^n + 6*6^n - 36*5^n + 36*4^n + 11*3^n - 22*2^n + 6). G.f.: -5*x^4*(517752*x^6 -251184*x^5 +4757*x^4 +12696*x^3 -1810*x^2 +24*x +5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)*(8*x -1)*(9*x -1)*(11*x -1)*(15*x -1)). - Colin Barker, Jul 11 2013 MATHEMATICA Table[(1/4!)*(15^n - 12*11^n + 24*9^n + 4*8^n - 18*7^n + 6*6^n - 36*5^n + 36*4^n + 11*3^n - 22*2^n + 6), {n, 0, 25}] (* G. C. Greubel, Oct 07 2017 *) PROG (PARI) for(n=0, 25, print1((15^n - 12*11^n + 24*9^n + 4*8^n - 18*7^n + 6*6^n - 36*5^n + 36*4^n + 11*3^n - 22*2^n + 6)/24, ", ")) \\ G. C. Greubel, Oct 07 2017 (MAGMA) [(15^n - 12*11^n + 24*9^n + 4*8^n - 18*7^n + 6*6^n - 36*5^n + 36*4^n + 11*3^n - 22*2^n + 6)/24: n in [0..25]]; // G. C. Greubel, Oct 07 2017 CROSSREFS Cf. A051112. Sequence in context: A023113 A322247 A177837 * A281436 A197671 A051112 Adjacent sequences:  A056044 A056045 A056046 * A056048 A056049 A056050 KEYWORD nonn,easy AUTHOR Vladeta Jovovic, Goran Kilibarda, Jul 25 2000 EXTENSIONS More terms from Colin Barker, Jul 11 2013 STATUS approved

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Last modified October 1 03:36 EDT 2020. Contains 337441 sequences. (Running on oeis4.)