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 A057782 #18 Jul 07 2023 14:36:48 %S A057782 1,9,94,1552,27285,509805,9783124 %N A057782 Building block is trapezoid formed from 3 equilateral triangles; sequence gives number of pieces (polytraps) that can be formed from n such trapezoids. %C A057782 Also known as "Polytriamonds" because the building block is the unique triamond (composite of three equilateral triangles joined edge-to-edge). - _Aaron N. Siegel_, May 23 2022 %D A057782 Computed by Brendan Owen. %H A057782 Abaroth's World, <a href="https://abarothsworld.com/Puzzles/Polyiamonds/Polyhes.htm">Polyhes, Polyhalfhexes & Polytriamonds</a> %H A057782 Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/PolyX/PolyX.htm">Other Polyforms</a> %Y A057782 Cf. A000577, A000228, A000105, A056844. %K A057782 nonn,nice,hard,more %O A057782 1,2 %A A057782 _N. J. A. Sloane_, Oct 29 2000 %E A057782 Link updated by _William Rex Marshall_, Dec 16 2009 %E A057782 a(7) from _Aaron N. Siegel_, May 23 2022