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 A081964 #9 Jun 05 2015 05:22:56 %S A081964 1,3,5,2,4,7,9,11,13,15,6,8,12,14,16,17,19,23,25,29,31,10,18,20,22,24, %T A081964 26,27,21,33,35,37,39,41,43,45,28,32,34,38,40,44,46,47,49,51,53,57,59, %U A081964 61,63,67,69,71,73,30,36,42,48,50,52,54,56,58,60,62,55,65,77,79,83,85 %N A081964 In the following triangle the n-th row contains n numbers relatively prime to n and not occurring in a previous row. a(1) = 1. Sequence contains the triangle by rows. %H A081964 Paul Tek, <a href="/A081964/b081964.txt">Table of n, a(n) for n = 1..10000</a> %H A081964 Paul Tek, <a href="/A081964/a081964.pl.txt">Perl program for this sequence</a> %e A081964 Triangle begins: %e A081964 1 %e A081964 3 5 %e A081964 2 4 7 %e A081964 9 11 13 15 %e A081964 6 8 12 14 16 %e A081964 ... %o A081964 (Perl) See Link section. %Y A081964 Cf. A081965, A081966. %Y A081964 Cf. A095167 (noncoprime instead of coprime). %K A081964 nonn,tabl %O A081964 1,2 %A A081964 _Amarnath Murthy_, Apr 03 2003 %E A081964 More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 08 2003