A100677 a(1) = 1; a(n) = sum{1<=k<=n/2, GCD(k,n)=1} a(k).

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

Offset

1,5

Links

Table of n, a(n) for n=1..70.

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);

Mathematica

a[1] = 1; a[n_] := a[n] = Plus @@ (a /@ Select[Range[n/2], GCD[ #, n] == 1 &]); Table[ a[n], {n, 70}] (* Robert G. Wilson v, Dec 09 2004 *)

Crossrefs

Sequence in context: A177501 A330926 A323273 * A188637 A083290 A121842

Adjacent sequences: A100674 A100675 A100676 * A100678 A100679 A100680

Keyword

nonn

Author

Leroy Quet, Dec 06 2004

Extensions

More terms from Emeric Deutsch and Robert G. Wilson v, Dec 09 2004

Status

approved