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%I #13 Oct 10 2019 11:52:00
%S 1,2,5,11,25,67,178,287,863,2092,5612,6871,22885,53613,69597,223822,
%T 385931,802877,2308019,5936156,12937623,29456690,81587807,166703456,
%U 437728341,973247233,2233938123,4919445412,13784085189,14842425156
%N a(1)=1. a(n) = a(n-1) + (sum of the earlier terms {among terms a(1) through a(n-1)} which are coprime to n).
%H Robert Israel, <a href="/A127075/b127075.txt">Table of n, a(n) for n = 1..3121</a>
%e The terms of the sequence, among terms a(1) through a(5), which are coprime to 6 are a(1)=1, a(3)=5, a(4)=11 and a(5)=25. So a(6) = a(5) +1 +5 +11 +25 = 67.
%p A[1]:= 1:
%p for n from 2 to 100 do
%p A[n]:= A[n-1]+convert(select(t -> igcd(t,n)=1, [seq(A[i],i=1..n-1)]),`+`)
%p od:
%p seq(A[i],i=1..100); # _Robert Israel_, Aug 23 2019
%t f[l_List] := Append[l, l[[ -1]] + Plus @@ Select[l, GCD[ #, Length[l] + 1] == 1 &]];Nest[f, {1}, 30] (* _Ray Chandler_, Jan 06 2007 *)
%Y Cf. A127076.
%K nonn
%O 1,2
%A _Leroy Quet_, Jan 04 2007
%E Extended by _Ray Chandler_, Jan 06 2007
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