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 A100675 a(1) = 1; for n >= 1, a(n+1) = sum{k=1..n} GCD(k,a(n)). 1
 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; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS MAPLE 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); MATHEMATICA 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) CROSSREFS Sequence in context: A072602 A049642 A050907 * A196730 A165569 A136803 Adjacent sequences:  A100672 A100673 A100674 * A100676 A100677 A100678 KEYWORD nonn AUTHOR Leroy Quet Dec 06 2004 EXTENSIONS More terms from Emeric Deutsch and Robert G. Wilson v, Dec 09 2004 Edited by N. J. A. Sloane at the suggestion of Andrew Plewe, Jun 16 2007 STATUS approved

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