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 A305704 #15 Feb 16 2025 08:33:54
%S A305704 6,8,9,12,15,16,18,20,21,22,24,25,27,28,30,32,33,34,35,36,38,39,40,42,
%T A305704 44,45,48,49,50,52,54,55,56,57,60,63,64,65,66,68,70,72,75,76,77,78,80,
%U A305704 81,82,84,85,86,87,88,90,91,93,95,96,98,99,100,102,104,105
%N A305704 Numbers that are the semiperimeter of some triangle with integer sides and area.
%H A305704 Peter Kagey, <a href="/A305704/b305704.txt">Table of n, a(n) for n = 1..1000</a>
%H A305704 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HeronianTriangle.html">Heronian Triangle</a>
%F A305704 a(n) = A051518(n)/2.
%t A305704 hp[p_] := Catch@ Block[{c, q=p/2}, Do[c = p-a-b; If[IntegerQ@ Sqrt[q (q-a) (q-b) (q-c)], Throw@ True], {a, p/2-1}, {b, p/2-a+1, p/2-1}]; False]; Select[Range@ 105, hp[2 #] &] (* _Giovanni Resta_, Jun 14 2018 *)
%Y A305704 Cf. A051518.
%K A305704 nonn
%O A305704 1,1
%A A305704 _Peter Kagey_, Jun 08 2018