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 A071979 #3 Dec 05 2013 19:55:20
%S A071979 1,3,7,11,18,25,43,51,67,81,104,119,152,167,199,227,258,277,330,351,
%T A071979 400,437,484,509,578,609,667,709,772,803,914,947,1010,1065,1136,1187,
%U A071979 1292,1331,1411,1477,1574,1619,1764,1809,1906,1989,2084,2135,2276,2333
%N A071979 Left diagonal of A071977.
%t A071979 a = {1}; k = 2; Do[i = 1; While[i < n + 1, If[ GCD[k, n] == 1, a = Append[a, k]; i++ ]; k++ ], {n, 2, 55}]; Table[ a[[n(n - 1)/2 + 1]], {n, 1, 55}]
%K A071979 nonn
%O A071979 1,2
%A A071979 _Amarnath Murthy_, Jun 18 2002
%E A071979 Edited by _Robert G. Wilson v_, Jun 28 2002