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Search: id:A005945
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| A005945 |
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Number of n-step mappings with 4 inputs.
(Formerly M4966)
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+0
3
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| 0, 1, 15, 60, 154, 315, 561, 910, 1380, 1989, 2755, 3696, 4830, 6175, 7749, 9570, 11656, 14025, 16695, 19684, 23010, 26691, 30745, 35190, 40044, 45325, 51051, 57240, 63910, 71079, 78765, 86986, 95760, 105105, 115039, 125580, 136746
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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a(n) is the coefficient of x^4/4! in n-th iteration of exp(x)-1.
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REFERENCES
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T. Hogg and B. A. Huberman, Attractors on finite sets: the dissipative dynamics of computing structures, Phys. Review A 32 (1985), 2338-2346. Math. Rev. 87e:58107
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FORMULA
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G.f.: x*(1+11*x+6*x^2)/(1-x)^4. a(n)=n*(3*n^2-5/2*n+1/2).
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PROGRAM
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(PARI) a(n)=if(n<0, 0, n*(3*n^2-5/2*n+1/2))
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CROSSREFS
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Adjacent sequences: A005942 A005943 A005944 this_sequence A005946 A005947 A005948
Sequence in context: A020187 A022287 A064761 this_sequence A110755 A001756 A022288
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KEYWORD
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nonn
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AUTHOR
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njas
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EXTENSIONS
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Edited by Michael Somos, Oct 29 2002
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