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 A285996 #47 May 28 2017 09:49:00 %S A285996 1,2,1,11,2,1,156,14,2,1 %N A285996 Triangle read by rows, 1<=k<=n, T(n,k) = number of arrangements of n circles in the affine plane having k separated islands. %C A285996 Consider the rules for the arrangements of n circles described in A250001. %C A285996 Note that T(4,1) = 156 includes the arrangement of 4 circles in which there is a little circle that is surrounded by the union of three solid circles, because the little circle is an inland island, or lake island, which does not count. So there is only one separated island. Hence T(4,2) = 14 does not include the mentioned arrangement. %C A285996 Question: is 1 together with the first column of the triangle the same as A275923? %e A285996 Triangle begins: %e A285996 1; %e A285996 2, 1; %e A285996 11, 2, 1; %e A285996 156, 14, 2, 1; %Y A285996 Another version of A252158. %Y A285996 Row sums give A250001, n >= 1. %Y A285996 Right border gives A000012. %Y A285996 Cf. A249752, A275923. %K A285996 nonn,tabl,hard,more %O A285996 1,2 %A A285996 _Omar E. Pol_, May 21 2017