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 A167274 #7 Apr 10 2013 13:42:03 %S A167274 1,3,1,3,0,1,1,3,3,1,3,0,0,0,1,1,3,0,0,3,1,1,0,3,0,3,0,1,3,1,1,3,1,3, %T A167274 3,1,3,0,0,0,0,0,0,0,1,1,3,0,0,0,0,0,0,3,1,1,0,3,0,0,0,0,0,3,0,1,3,1, %U A167274 1,3,0,0,0,0,1,3,3,1 %N A167274 Triangle read by rows, = 2*A047999 - A047999^(-1); = twice Sierpinski's gasket minus the inverse of Sierpinski's gasket. %C A167274 Row sums = A167275: (1, 4, 4, 8, 4, 8, 8,...). %F A167274 Let Sierpinski's gasket, A047999 = S; as an infinite lower triangular matrix. %F A167274 A167274 = 2*S - 1/S. %e A167274 First few rows of the triangle = %e A167274 1; %e A167274 3, 1; %e A167274 3, 0, 1; %e A167274 1, 3, 3, 1; %e A167274 3, 0, 0, 0, 1; %e A167274 1, 3, 0, 0, 3, 1; %e A167274 1, 0, 3, 0, 3, 0, 1; %e A167274 3, 1, 1, 3, 1, 3, 3, 1; %e A167274 3, 0, 0, 0, 0, 0, 0, 0, 1; %e A167274 1, 3, 0, 0, 0, 0, 0, 0, 3, 1; %e A167274 1, 0, 3, 0, 0, 0, 0, 0, 3, 0, 1; %e A167274 3, 1, 1, 3, 0, 0, 0, 0, 1, 3, 3, 1; %e A167274 1, 0, 0, 0, 3, 0, 0, 0, 3, 0, 0, 0, 1; %e A167274 3, 1, 0, 0, 1, 3, 0, 0, 1, 3, 0, 0, 3, 1; %e A167274 3, 0, 1, 0, 1, 0, 3, 0, 1, 0, 3, 0, 3, 0, 1 %e A167274 1, 3, 3, 1, 3, 1, 1, 3, 3, 1, 1, 3, 1, 3, 3, 1; %e A167274 ... %Y A167274 Cf. A047999, A167275 %K A167274 nonn,tabl %O A167274 0,2 %A A167274 _Gary W. Adamson_ & _Mats Granvik_, Oct 31 2009