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Search: id:A100675
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| A100675 |
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a(1) = 1; for n >= 1, a(n+1) = sum{k=1..n} GCD(k,a(n)). |
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+0
2
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| 1, 1, 2, 4, 8, 9, 10, 14, 18, 27, 22, 26, 18, 37, 14, 40, 56, 59, 18, 64, 56, 73, 22, 64, 68, 65, 70, 92, 78, 105, 126, 148, 64, 113, 34, 100, 140, 199, 38, 112, 170, 157, 42, 196, 154, 181, 46, 136, 168, 309, 82, 116, 132, 271, 54, 244, 112, 285, 254, 88, 238, 227, 62
(list; graph; listen)
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OFFSET
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1,3
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MAPLE
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a[1]:=1: for n from 2 to 80 do b[n]:=[seq(gcd(k, a[n-1]), k=1..n-1)]: a[n]:=sum(b[n][j], j=1..nops(b[n])) od: seq(a[n], n=1..80);
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MATHEMATICA
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a[1] = 1; a[n_] := a[n] = Plus @@ GCD[Table[i, {i, n - 1}], a[n - 1]]; Table[ a[n], {n, 62}] (from Robert G. Wilson v Dec 09 2004)
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CROSSREFS
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Adjacent sequences: A100672 A100673 A100674 this_sequence A100676 A100677 A100678
Sequence in context: A072602 A049642 A050907 this_sequence A136803 A035268 A035241
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Dec 06 2004
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu) and Robert G. Wilson v, Dec 09 2004
Edited by njas at the suggestion of Andrew Plewe, Jun 16 2007
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