A127077 a(1)=1. a(n) = a(n-1) + (product of the earlier terms {among terms a(1) through a(n-1)} which are coprime to n).

1, 2, 4, 5, 13, 78, 40638, 40703, 21206263, 11221082003820, 15964509207021745126354079410538220, 15964509207021745126410184714526005

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Example

The terms of the sequence, among terms a(1) through a(5), which are coprime to 6 are a(1)=1, a(4)=5 and a(5) = 13. So a(6) = a(5) + 1*5*13 = 78.

Mathematica

f[l_List] := Append[l, l[[ -1]] + Times @@ Select[l, GCD[ #, Length[l] + 1] == 1 &]]; Nest[f, {1}, 15] (* Ray Chandler, Jan 06 2007 *)

Crossrefs

Cf. A127078.

Sequence in context: A273097 A232207 A136563 * A367027 A104549 A174513

Adjacent sequences: A127074 A127075 A127076 * A127078 A127079 A127080

Keyword

nonn

Author

Leroy Quet, Jan 04 2007

Extensions

Extended by Ray Chandler, Jan 06 2007

Status

approved