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 A048223 #8 Jun 06 2021 02:52:30 %S A048223 4,4,11,19,29,39,54,72,89,113,137,163,189,216,254,288,323,363,402,446, %T A048223 495,544,593,651,710,772,835,898,964,1036,1106,1185,1263,1341,1420, %U A048223 1504,1591,1681,1770,1860,1963,2063,2165,2271,2378 %N A048223 a(n)=T(n,1)+T(n,n), array T given by A048212. %F A048223 a(n) = 2*A004979(n+1) - A004979(n) - 1. - _Sean A. Irvine_, Jun 05 2021 %Y A048223 Cf. A004979. %K A048223 nonn %O A048223 1,1 %A A048223 _Clark Kimberling_