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A129282
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a(0)=1; for n > 1, a(n) = a(n-1) + (the largest value of gcd(a(k),n) for 0 <= k <= n-1).
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2
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1, 2, 4, 5, 9, 14, 17, 24, 32, 41, 46, 47, 59, 60, 74, 89, 105, 122, 131, 132, 152, 173, 195, 218, 242, 247, 260, 269, 283, 284, 314, 315, 347, 380, 397, 432, 468, 505, 543, 582, 602, 643, 664, 707, 751, 796, 842, 889, 937, 944, 954, 971, 1023, 1076, 1130, 1141
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OFFSET
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0,2
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LINKS
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EXAMPLE
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For those k where 0 <= k <= 9, gcd(a(3),10) = 5 is the largest value for a gcd(a(k),10). So a(10) = a(9) + 5 = 46.
For those k where 0 <= k <= 11, gcd(a(7),12) = 12 is the largest value for a gcd(a(k),12). So a(12) = a(11) + 12 = 59.
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MAPLE
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a[0]:=1: for n from 1 to 70 do a[n]:=a[n-1]+max((seq(gcd(a[k], n), k=0..n-1))) od: seq(a[n], n=0..70); # Emeric Deutsch, Apr 11 2007
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MATHEMATICA
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Fold[Append[#1, #1[[-1]] + Max@GCD[#1, #2]] &, {1}, Range[55]] (* Ivan Neretin, Oct 24 2018 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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