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 A385977 #3 Jul 13 2025 21:53:04 %S A385977 4,112,3444,114720,3883684,131852560,4478648724,152139554112, %T A385977 5168250745924,175568295786160,5964153281301684,202605640210401120, %U A385977 6882627596048598244,233806732521557580112,7942546277531426709204,269812766700017940393600,9165691521502509968254084 %N A385977 Length of the long leg of the triangles defined in A377725. %F A385977 a(n) = 2 * A002315(n) * (A002315(n) + 1). %Y A385977 Cf. A002315, A377725. %K A385977 nonn,easy %O A385977 1,1 %A A385977 _Sean A. Irvine_, Jul 13 2025