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Search: id:A125596
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| A125596 |
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a(1)=1. a(n) = sum{1<=k<n, GCD(k,n(n+1))=1} a(k). |
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+0
2
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| 1, 1, 1, 2, 1, 2, 3, 5, 4, 9, 5, 10, 12, 18, 21, 48, 22, 44, 48, 88, 84, 197, 92, 183, 260, 432, 441, 908, 183, 366, 1178, 1800, 1778, 3743, 1541, 3346, 5627, 8913, 7159, 16638, 7429, 14858, 24107, 38702, 38615, 88520, 40509, 79474, 88596, 167790, 169580
(list; graph; listen)
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OFFSET
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1,4
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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The positive integers < 8 and coprime to 8 and 9 are 1,5,7. So a(8) = a(1)+a(5)+a(7) = 1+1+3 = 5.
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MATHEMATICA
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f[l_List] := Block[{n = Length[l] + 1}, Append[l, Plus @@ l[[Select[Range[n], GCD[ #, n*(n + 1)] == 1 &]]]]]; Nest[f, {1}, 50] (*Chandler*)
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CROSSREFS
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Cf. A125597.
Sequence in context: A127462 A106436 A075758 this_sequence A132405 A057192 A078777
Adjacent sequences: A125593 A125594 A125595 this_sequence A125597 A125598 A125599
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Nov 26 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 26 2006
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