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 A127078 a(0)=1. a(n) = a(n-1) + (product of the earlier terms {among terms a(0) through a(n-1)} which are coprime to n). 1

%I #9 Oct 10 2019 11:51:01

%S 1,2,3,5,20,26,31,483631,225372046,17570301566444363246,

%T 17570301566489340929,

%U 16272673148565174391333181067098727985892644426731405243329

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

%e The terms of the sequence, among terms a(0) through a(5), which are coprime to 6 are a(0)=1 and a(3)=5. So a(6) = a(5) + 1*5 = 31.

%t f[l_List] := Append[l, l[[ -1]] + Times @@ Select[l, GCD[ #, Length[l]] == 1 &]];Nest[f, {1}, 13] (* _Ray Chandler_, Jan 06 2007 *)

%Y Cf. A127077.

%K nonn

%O 0,2

%A _Leroy Quet_, Jan 04 2007

%E Extended by _Ray Chandler_, Jan 06 2007

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Last modified May 29 00:21 EDT 2023. Contains 363029 sequences. (Running on oeis4.)