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 A177144 #4 Jun 02 2025 02:54:11 %S A177144 1,4,9,19,38,69,134,289,520,1076,2134,4098,8376,16559,33020,66114, %T A177144 132119,263585,525765,1050309,2097946,4199226,8394235,16785959 %N A177144 A156790(n+1)-4*A156790(n). %Y A177144 Cf. A156790. %K A177144 nonn %O A177144 0,2 %A A177144 _Jaume Oliver Lafont_, May 03 2010