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 A353578 #13 Jul 09 2022 21:46:44 %S A353578 3,7,15,27,31,51,55,59,63,103,111,115,119,123,127,207,219,223,231,239, %T A353578 243,247,251,255,411,415,435,439,443,447,463,475,479,487,495,499,503, %U A353578 507,511,819,823,827,831,871,879,883,887,891,895,923,927,947,951,955,959,975,987,991,999,1007,1011,1015,1019,1023 %N A353578 Numbers in the smallest subset of N containing 3 and closed under the mappings k->2k + 1, k->8k + 3, and k->16k + 3. %H A353578 Paul K. Stockmeyer, <a href="/A353578/b353578.txt">Table of n, a(n) for n = 1..1155</a> %H A353578 Andreas M. Hinz and Paul K. Stockmeyer, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL25/Hinz/hinz5.html">Precious Metal Sequences and Sierpinski-Type Graphs</a>, J. Integer Seq., Vol 25 (2022), Article 22.4.8. %K A353578 nonn %O A353578 1,1 %A A353578 _Paul K. Stockmeyer_, May 03 2022