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Search: id:A080369
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| A080369 |
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a(n) is the value of Vandermonde determinant for lexicographically first n-mark Golomb-ruler. |
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+0
1
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| 1, 1, 6, 720, 6652800, 1693749657600, 367216146859161600000, 1888288177044984240734208000000, 4157567140515322460268246337585152000000000
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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a(n)=Product[a(i)-a(j)], j<i<=n; product of C[n, 2] positive differences provided by the n marks of ruler.
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EXAMPLE
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n=6:the ruler={1,2,5,11,13,18}, the C[6,2]=15 possible differences={17,16,13,7,5,12,11,8,2,10,9,6,4,3,1}; the product = a(6)=1693749657600.
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MATHEMATICA
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t={marks of ruler}; lt=Length[t] b[x_] := Part[t, x] bd[x_] := Reverse[b[x]-Table[b[j], {j, 1, x-1}]] pb[x_] := Apply[Times, bd[x]] Table[{j, bd[j], pb[j]}, {j, 1, lt}]; vm=Table[Apply[Times, Table[pb[u], {u, 1, k}]], {k, 1, lt}]; Part[vm, lt]
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CROSSREFS
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Cf. A031869-A031875.
Sequence in context: A003923 A002204 A052295 this_sequence A036981 A130688 A088217
Adjacent sequences: A080366 A080367 A080368 this_sequence A080370 A080371 A080372
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Feb 24 2003
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