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 A330850 #25 May 31 2020 05:50:09 %S A330850 45,69,119,219,357,575,871,1301,1815,2543,3435,4635,6023,7731,9727, %T A330850 12259,15087,18585,22543,27165,32215,38239,44899,52631,60979,70465, %U A330850 80815,92749,105511,120079,135867,153331,171851,192311,214159,238583,264323,292371,322171 %N A330850 The number of vertices inside a cross with width 3 and height n (see Comments in A331455 for definition) formed by the straight line segments mutually connecting all vertices and all points. %C A330850 See the links in A331455 for images of the crosses. %H A330850 Lars Blomberg, <a href="/A330850/b330850.txt">Table of n, a(n) for n = 2..50</a> %Y A330850 Cf. A331455 (regions), A330848 (n-gons), A330851 (edges), A333035 (cross with equal length arms). %K A330850 nonn %O A330850 2,1 %A A330850 _Scott R. Shannon_ and _N. J. A. Sloane_, Mar 07 2020 %E A330850 Corrected offset and a(11) and beyond from _Lars Blomberg_, May 31 2020