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 A048449 #6 Oct 14 2019 23:43:48 %S A048449 7,13,23,30,44,52,68,80,94,114,126,146,160,176,194,210,232,246,266, %T A048449 282,296,318,336,358,380,398,412,428,448,464,500,514,550,560,592,604, %U A048449 630,650,670,690,716,728,758,766,796,814,846,874,898,920,934,958,972,1004 %N A048449 Starting from generation 2 add previous and next term yielding generation 3. %Y A048449 Generation 2 is A048448. See A048448-A048466. See also A047844. %K A048449 nonn %O A048449 0,1 %A A048449 _Patrick De Geest_, May 15 1999