%I #29 Aug 13 2017 08:09:33

%S 7,15,28,60,112,240

%N Idoneal numbers (A000926) that are not pentagon exception numbers (A229461).

%C See A229461.

%C Idoneal numbers not of the form 7 or 15 times a square. - _Hugo Pfoertner_, Aug 13 2017

%H Eike Hertel, <a href="http://www.minet.uni-jena.de/preprints/hertel_13/Regdreipfla.pdf">Reguläre Dreieckspflasterungen konvexer Polygone</a>, Jenaer Schriften zur Mathematik und Informatik Math/Inf/01/13, 2013 (Preprint).

%H Eike Hertel, Christian Richter, <a href="https://doi.org/10.1007/s00454-014-9576-7">Tiling Convex Polygons with Congruent Equilateral Triangles</a>, Discrete Comput Geom (2014) 51:753-759.

%H MathOverflow, <a href="https://mathoverflow.net/questions/188977/which-natural-numbers-are-a-square-minus-a-sum-of-two-squares">Which natural numbers are a square minus a sum of two squares?</a>. Answer by user "Lucia", 2014 Dec 5.

%Y Cf. A000926 (idoneal numbers), A229461 (pentagon exception numbers).

%K nonn,fini,full

%O 1,1

%A Suggested by Eike Hertel, _Hugo Pfoertner_, Sep 24 2013