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 A065225 #12 Nov 01 2024 15:08:23 %S A065225 1,2,5,9,5,11,18,2,11,21,32,44,11,25,40,56,73,16,35,55,76,98,10,34,59, %T A065225 85,112,140,15,45,76,108,141,175,6,42,79,117,156,196,237,18,61,105, %U A065225 150,196,243,291,15,65,116,168,221,275,330,386,47,105,164,224,285,347,410 %N A065225 Fill a triangular array by rows by writing numbers 1 up to b(0), 1 up to b(1), etc., where b(n) are the 9-gonal (nonagonal) numbers. The final elements of the rows form a(n). %Y A065225 Cf. A001106. %Y A065225 Mini-index to these sequences: A064766, A064865, A064866, A065221-A655234 are all of the same type. See A064766 for a detailed explanation. %K A065225 easy,nonn %O A065225 0,2 %A A065225 _Floor van Lamoen_, Oct 22 2001