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Search: id:A125120
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| A125120 |
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Sum of values of repunits of length n in base b representation with 1<b<=n+1. |
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+0
2
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| 1, 7, 41, 296, 2829, 34637, 519049, 9197344, 188039787, 4356087231, 112754069273, 3224945523736, 100999970565337, 3437517630509497, 126332966608699441, 4986057436997869696, 210331809309776028055, 9443995455881145458715
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OFFSET
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1,2
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COMMENT
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Sums of rows of the triangle in A125118: a(n)=Sum(A125118(n,k):1<=k<=n).
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LINKS
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Eric Weisstein's World of Mathematics, Repunit
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FORMULA
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a(n) = Sum(Sum((k+1)^i: 0<=i<k): 1<=k<=n).
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EXAMPLE
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a(4) = [1111]_2 + [1111]_3 + [1111]_4 + [1111]_5 =
((2+1)*2+1)*2+1 + ((3+1)*3+1)*3+1 + ((4+1)*4+1)*4+1 +
((5+1)*5+1)*5+1 = 296.
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CROSSREFS
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Sequence in context: A115137 A036730 A080047 this_sequence A053676 A002701 A057006
Adjacent sequences: A125117 A125118 A125119 this_sequence A125121 A125122 A125123
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KEYWORD
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nonn,base
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)AT)lhsystems.com), Nov 21 2006
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