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 A238381 #15 Aug 13 2020 14:02:28 %S A238381 0,1,2,3,4,6,8,11,14,18,21,25,30,35,40 %N A238381 Minimal number of V-trominoes needed to prevent any further V-trominoe from being placed on an n X n grid. %C A238381 The V-trominoes must line up with the squares on the grid (skew placements are not allowed). %C A238381 a(n) is the independent domination number of a graph with one node per tromino and an edge for each pair of trominoes that conflict. - _Rob Pratt_, Oct 02 2019 %H A238381 Juris Cernenoks, <a href="/A238381/a238381.png">Illustration of initial terms</a> %H A238381 Erich Friedman, <a href="https://erich-friedman.github.io/mathmagic/0600.html">Problem of the Month (June 2000)</a> %Y A238381 Cf. A226918. %K A238381 nonn,more %O A238381 1,3 %A A238381 _Juris Cernenoks_, Feb 25 2014 %E A238381 a(13)-a(15) from _Rob Pratt_, Oct 02 2019