This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A130700 #16 Jul 30 2025 19:32:06
%S A130700 1,1,3,4,7,6,17,8,15,16,23,12,35,19,33,31,33,29,55,27,73,37,49,27,71,
%T A130700 31,57,43,67,30,109,32,63,64,71,51,113,38,79,62,103,42,145,56,111,88,
%U A130700 105,106,145,73,127
%N A130700 a(0)=1; a(n) is the n-th integer from among those positive integers which are coprime to (a(n-1)*n).
%H A130700 Robert Israel, <a href="/A130700/b130700.txt">Table of n, a(n) for n = 0..10000</a>
%e A130700 a(8)*9 = 135. Those positive integers which are coprime to 135 form the sequence: 1,2,4,7,8,11,13,14,16,17,19,22,... The 9th of these integers is 16, so a(9) = 16.
%p A130700 a[0]:=1: for n to 50 do CP:={}: for j while nops(CP)<=n do if gcd(n*a[n-1],j) =1 then CP:=`union`(CP,{j}) else end if end do: a[n]:=CP[n] end do: seq(a[n], n=0..50); # _Emeric Deutsch_, Aug 28 2007
%Y A130700 Cf. A069213.
%K A130700 nonn,look
%O A130700 0,3
%A A130700 _Leroy Quet_, Aug 12 2007
%E A130700 More terms from _Emeric Deutsch_, Aug 28 2007