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A223659
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Number of unimodal maps [1..n]->[0..3].
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19
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1, 4, 16, 50, 130, 296, 610, 1163, 2083, 3544, 5776, 9076, 13820, 20476, 29618, 41941, 58277, 79612, 107104, 142102, 186166, 241088, 308914, 391967, 492871, 614576, 760384, 933976, 1139440, 1381300, 1664546, 1994665, 2377673, 2820148, 3329264
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = (1/720)*n^6 + (1/48)*n^5 + (23/144)*n^4 + (9/16)*n^3 + (241/180)*n^2 + (11/12)*n + 1 = 1 + n*(n+1)*(n^4 + 14*n^3 + 101*n^2 + 304*n + 660)/720.
Empirical g.f.: 1-x*(x^2-2*x+2)*(x^4-4*x^3+6*x^2-4*x+2) / (x-1)^7. - R. J. Mathar, May 14 2014
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EXAMPLE
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Some solutions for n=3:
2 2 0 1 1 3 1 0 3 1 2 1 2 1 0 2
2 2 1 3 3 3 3 2 2 2 2 3 0 1 1 1
2 0 2 2 0 1 3 3 1 0 3 1 0 1 1 0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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