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A038233
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Triangle whose (i,j)-th entry is binomial(i,j)*4^(i-j)*3^j.
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1
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1, 4, 3, 16, 24, 9, 64, 144, 108, 27, 256, 768, 864, 432, 81, 1024, 3840, 5760, 4320, 1620, 243, 4096, 18432, 34560, 34560, 19440, 5832, 729, 16384, 86016, 193536, 241920, 181440, 81648, 20412, 2187, 65536, 393216, 1032192, 1548288
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OFFSET
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0,2
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COMMENTS
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T(i,j) is the number of sequences (X_1, X_2, X_3) of subsets of {1,2,...,i} such that X_1 intersect X_2 intersect X_3 is empty and X_3 contains exactly j elements. Cf. Stanley reference. - Geoffrey Critzer, Jan 11 2016
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REFERENCES
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B. N. Cyvin et al., Isomer enumeration of unbranched catacondensed polygonal systems with pentagons and heptagons, Match, No. 34 (Oct 1996), pp. 109-121.
R. P. Stanley, Enumerative Combinatorics Vol I, Cambridge Univ. Press, 1997, page 11.
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LINKS
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FORMULA
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EXAMPLE
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1;
4, 3;
16, 24, 9;
64, 144, 108, 27;
256, 768, 864, 432, 81;
1024, 3840, 5760, 4320, 1620, 243;
4096, 18432, 34560, 34560, 19440, 5832, 729;
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MATHEMATICA
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nn = 10; Map[Select[#, # > 0 &] &, Range[0, nn]! CoefficientList[
Series[Exp[3 x + 3 y x] Exp[x], {x, 0, nn}], {x, y}]] // Grid (* Geoffrey Critzer, Jan 11 2016 *)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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