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 A090172 #8 Apr 20 2015 04:04:59 %S A090172 1,0,0,1,1,1,1,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,1,1,1,0,1,0,0,1,0,0,1, %T A090172 0,0,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,0,1,0,1,1,1,1,1,0,1,0,1,0, %U A090172 1,1,1,1,1,1,1,1,0,1,1,0,0,0,0,1,1,1,0,0,0,0,1,0,0,0,0,1,0,1,1,0,1,0,0,0,0 %N A090172 Triangle read by rows, related to Pascal's triangle read mod 2. %H A090172 Y. Moshe, <a href="http://dx.doi.org/10.1016/S0022-314X(03)00103-3">The density of 0's in recurrence double sequences</a>, J. Number Theory, 103 (2003), 109-121; see Fig. 2. %F A090172 a(n, k) = A091562(n, k) mod 2. %e A090172 1; 0,0; 1,1,1; 1,0,0,1; 0,1,1,1,0; ... %Y A090172 Row sums: A091563. Cf. A007318, A083093, A090171-A090174. %K A090172 nonn,easy,tabl %O A090172 0,1 %A A090172 _N. J. A. Sloane_, Jan 19 2004 %E A090172 Edited and extended by _Christian G. Bower_, Jan 20 2004