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A055484
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Number of unlabeled 3-element intersecting families (with not necessary distinct sets) of an n-element set.
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2
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1, 4, 14, 39, 96, 213, 437, 837, 1520, 2632, 4380, 7040, 10979, 16668, 24716, 35879, 51104, 71549, 98625, 134025, 179782, 238292, 312386, 405368, 521083, 663968, 839140, 1052439, 1310534, 1620985, 1992343, 2434229, 2957458, 3574108
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| V. Jovovic, 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).
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FORMULA
| G.f. : -x*(x^3-x^2-1)*(x^6+x^4+2*x^3+x^2+1)/((x^3-1)^2*(x^2-1)^2*(x-1)^4).
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CROSSREFS
| Cf. A053155 (labeled case), A005783, A002727, A051180.
Sequence in context: A114845 A064463 A130423 * A055279 A074083 A182819
Adjacent sequences: A055481 A055482 A055483 * A055485 A055486 A055487
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic, Goran Kilibarda (vladeta(AT)eunet.rs), Jul 03 2000
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 04 2000
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