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A100677
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a(1) = 1; a(n) = sum{1<=k<=n/2, GCD(k,n)=1} a(k).
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0
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1, 1, 1, 1, 2, 1, 3, 2, 3, 2, 6, 3, 7, 4, 6, 7, 12, 6, 15, 8, 9, 10, 23, 12, 22, 16, 25, 20, 37, 17, 43, 29, 30, 29, 45, 31, 68, 41, 56, 48, 91, 43, 100, 59, 69, 65, 133, 69, 129, 80, 114, 103, 183, 91, 152, 123, 147, 135, 265, 104, 282, 172, 215, 215, 274, 165, 384, 233, 277, 203
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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MAPLE
| a[1]:=1: for n from 2 to 74 do b:=0: for k from 1 to n/2 do if gcd(k, n)=1 then b:=b+a[k] else b:=b fi od: a[n]:=b: od: seq(a[n], n=1..74);
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MATHEMATICA
| a[1] = 1; a[n_] := a[n] = Plus @@ (a /@ Select[Range[n/2], GCD[ #, n] == 1 &]); Table[ a[n], {n, 70}] (from Robert G. Wilson v Dec 09 2004)
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CROSSREFS
| Sequence in context: A078709 A023022 A177501 * A188637 A083290 A121842
Adjacent sequences: A100674 A100675 A100676 * A100678 A100679 A100680
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Dec 06 2004
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu) and Robert G. Wilson v, Dec 09 2004
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