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 A280784 #11 May 02 2020 07:33:47 %S A280784 1,2,1,5,3,1,13,9,3,1,35,26,10,3,1,95,75,30,10,3,1,262,214,91,31,10,3, %T A280784 1,727,612,268,95,31,10,3,1,2033,1747,790,284,96,31,10,3,1,5714,4995, %U A280784 2308,848,288,96,31,10,3,1,16136,14294,6737,2506,864,289,96,31,10,3,1 %N A280784 Triangle read by rows: numbers of nonintersecting circles with one of them marked. %H A280784 R. J. Mathar, <a href="http://arxiv.org/abs/1603.00077">Topologically Distinct Sets of Non-intersecting Circles in the Plane</a>, arXiv:1603.00077 [math.CO], 2016. %e A280784 Triangle begins: %e A280784 1, %e A280784 2,1, %e A280784 5,3,1, %e A280784 13,9,3,1, %e A280784 35,26,10,3,1, %e A280784 95,75,30,10,3,1, %e A280784 262,214,91,31,10,3,1, %e A280784 727,612,268,95,31,10,3,1, %e A280784 2033,1747,790,284,96,31,10,3,1, %e A280784 ... %Y A280784 Rows sums are A000243. %K A280784 nonn,tabl %O A280784 1,2 %A A280784 _N. J. A. Sloane_, Jan 20 2017