|
%I #13 Sep 15 2020 21:07:39
%S 1,2,3,6,10,22,23,90,117,175,319,746,1264,3925,8313,10690,23566,64525,
%T 133493,380783,903835,2427039,6349271,16657466,24493816,74970066,
%U 84860988,133884920,144156567,630996725,637860615,2396049996,3819335725
%N 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).
%H Robert Israel, <a href="/A127076/b127076.txt">Table of n, a(n) for n = 0..3125</a>
%e 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.
%p R:= [1]:
%p for n from 1 to 100 do
%p x:= R[-1] + convert(select(t -> igcd(t,n)=1, R),`+`);
%p R:= [op(R),x];
%p od:
%p R; # _Robert Israel_, Sep 15 2020
%t f[l_List] := Append[l, l[[ -1]] + Plus @@ Select[l, GCD[ #, Length[l]] == 1 &]];Nest[f, {1}, 32] (* _Ray Chandler_, Jan 06 2007 *)
%Y Cf. A127075.
%K nonn
%O 0,2
%A _Leroy Quet_, Jan 04 2007
%E Extended by _Ray Chandler_, Jan 06 2007
|
