A127076 a(0)=1. a(n) = a(n-1) + (sum of the earlier terms {among terms a(0) through a(n-1)} which are coprime to n).

1, 2, 3, 6, 10, 22, 23, 90, 117, 175, 319, 746, 1264, 3925, 8313, 10690, 23566, 64525, 133493, 380783, 903835, 2427039, 6349271, 16657466, 24493816, 74970066, 84860988, 133884920, 144156567, 630996725, 637860615, 2396049996, 3819335725

Offset

0,2

Links

Robert Israel, Table of n, a(n) for n = 0..3125

Example

The terms of the sequence, among terms a(0) through a(7), which are coprime to 8 are a(0)=1, a(2)=3 and a(6) = 23. So a(8) = a(7) +1 +3 +23 = 117.

Maple

R:= [1]:
for n from 1 to 100 do
  x:= R[-1] + convert(select(t -> igcd(t, n)=1, R), `+`);
  R:= [op(R), x];
od:
R; # Robert Israel, Sep 15 2020

Mathematica

f[l_List] := Append[l, l[[ -1]] + Plus @@ Select[l, GCD[ #, Length[l]] == 1 &]]; Nest[f, {1}, 32] (* Ray Chandler, Jan 06 2007 *)

Crossrefs

Cf. A127075.

Sequence in context: A036650 A049889 A014270 * A137208 A049527 A074371

Adjacent sequences: A127073 A127074 A127075 * A127077 A127078 A127079

Keyword

nonn

Author

Leroy Quet, Jan 04 2007

Extensions

Extended by Ray Chandler, Jan 06 2007

Status

approved