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 A143417 #6 Jan 28 2014 00:49:33 %S A143417 1,2,3,4,6,8,12,24,5,10,15,16,20,30,40,48,60,80,120,240,7,9,14,18,21, %T A143417 28,36,42,56,63,72,84,126,168,252,504,32,96,160,480,11,22,33,44,66,88, %U A143417 132,264,13,26,35,39,45,52,65,70,78,90,91,104,105,112,117,130,140,144,156 %N A143417 Irregular triangle in which row n gives the k such that the reduced totient function psi(k) = A002174(n). %C A143417 Row n consists of the divisors of A143407(n) that are not divisors of A143407(r) for r<n. The length of row n is A143408(n). %H A143417 T. D. Noe, <a href="/A143417/b143417.txt">Rows n=1..20, flattened</a> %e A143417 1,2; 3,4,6,8,12,24; 5,10,15,16,20,30,40,48,60,80,120,240 %Y A143417 Cf. A002322 (reduced totient function). %K A143417 nonn,tabf,look %O A143417 1,2 %A A143417 _T. D. Noe_, Aug 13 2008