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 A355949 #11 Jul 22 2022 16:44:03 %S A355949 5,25,81,157,301,381,665,821,1109,1353,1825,1861,2621,2881,3285,3813, %T A355949 4645,4773,5873,5953,6821,7665,8761,8613,10165,10921,11777,12337, %U A355949 14173,13717,16265,16581,17861,19161,20093,20461,23405,24145,25305,25701,28885,28433,31841,32077,33269,35841,38185 %N A355949 Number of vertices formed in a square by straight line segments when connecting the four corner vertices to the points dividing the sides into n equal parts. %H A355949 Scott R. Shannon, <a href="/A355949/a355949.png">Image for n = 2</a>. %H A355949 Scott R. Shannon, <a href="/A355949/a355949_1.png">Image for n = 3</a>. %H A355949 Scott R. Shannon, <a href="/A355949/a355949_2.png">Image for n = 4</a>. %H A355949 Scott R. Shannon, <a href="/A355949/a355949_3.png">Image for n = 5</a>. %H A355949 Scott R. Shannon, <a href="/A355949/a355949_4.png">Image for n = 6</a>. %H A355949 Scott R. Shannon, <a href="/A355949/a355949_5.png">Image for n = 11</a>. %F A355949 a(n) = A355948(n) - A108914(n) + 1 by Euler's formula. %Y A355949 Cf. A108914 (regions), A355948 (edges), A355992 (k-gons), A355839, A331452, A335678. %K A355949 nonn %O A355949 1,1 %A A355949 _Scott R. Shannon_, Jul 21 2022