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 A305705 #15 May 25 2019 02:04:00 %S A305705 1,2,3,4,5,7,10,11,13,14,17,19,23,26,29,31,37,41,43,46,47,51,53,58,59, %T A305705 61,62,67,69,71,73,74,79,83,89,92,94,97,101,103,106,107,109,113,122, %U A305705 123,127,131,137,139,141,142,149,151,157,158,163,167,173,179,181 %N A305705 Positive integers which are not the semiperimeter of any triangle with integer sides and area. %H A305705 Peter Kagey, <a href="/A305705/b305705.txt">Table of n, a(n) for n = 1..1000</a> %F A305705 a(n) = A305703(n)/2. %Y A305705 Complement of A305704. %Y A305705 Cf. A051518, A305703. %K A305705 nonn %O A305705 1,2 %A A305705 _Peter Kagey_, Jun 08 2018