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 A143655 #2 Mar 30 2012 17:25:32 %S A143655 0,0,0,0,2,0,0,0,3,0,0,2,3,0,0,0,0,0,0,5,0,0,2,3,0,5,0,0,0,0,3,0,5,0, %T A143655 7,0,0,2,0,0,5,0,7,0,0,0,0,3,0,0,0,7,0,0,0,0,2,3,0,5,0,7,0,0,0,0,0,0, %U A143655 0,0,5,0,7,0,0,0,11,0,0,2,3,0,5,0,7,0,0,0,11,0,0,0,0,3,0,5,0,0,0,0,0,11,0 %N A143655 Triangle read by rows, primes not dividing n; A054521 * (A061397 * 0^(n-k)), 1<=k<=n. %C A143655 Row sums = A066911: (0, 0, 2, 3, 5, 5, 10, 15, 14,....) %F A143655 Triangle read by rows, A054521 * (A061397 * 0^(n-k)), 1<=k<=n. T(n,k) = prime if k is prime but does not divide n. A054521 = a triangle with row sums phi(n). A061397 = (0, 2, 3, 0, 5, 0, 7,...) %e A143655 First few rows of the triangle = %e A143655 0; %e A143655 0, 0; %e A143655 0, 2, 0; %e A143655 0, 0, 3, 0; %e A143655 0, 2, 3, 0, 0; %e A143655 0, 0, 0, 0, 5, 0; %e A143655 0, 2, 3, 0, 5, 0, 0; %e A143655 0, 0, 3, 0, 5, 0, 7, 0; %e A143655 ... %e A143655 Row 8 has 3 primes < 8 not dividing 8: (3, 5, 7); where (3 + 5 + 7) = A066911(8). %Y A143655 Cf. A061397, A066911, A054521. %K A143655 nonn,tabl %O A143655 1,5 %A A143655 _Gary W. Adamson_, Aug 28 2008