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 A305703 #12 May 25 2019 02:04:04 %S A305703 2,4,6,8,10,14,20,22,26,28,34,38,46,52,58,62,74,82,86,92,94,102,106, %T A305703 116,118,122,124,134,138,142,146,148,158,166,178,184,188,194,202,206, %U A305703 212,214,218,226,244,246,254,262,274,278,282,284,298,302,314,316 %N A305703 Positive even integers that are not the perimeter of any Heronian triangle. %C A305703 Equivalently, this sequence is all positive even numbers that are not in A051518. %C A305703 Contains all even semiprimes (A100484). %H A305703 Peter Kagey, <a href="/A305703/b305703.txt">Table of n, a(n) for n = 1..1000</a> %Y A305703 Cf. A051518, A100484. %K A305703 nonn %O A305703 1,1 %A A305703 _Peter Kagey_, Jun 08 2018