A229462 Idoneal numbers (A000926) that are not pentagon exception numbers (A229461).

7, 15, 28, 60, 112, 240

Offset

1,1

Comments

See A229461.

Idoneal numbers not of the form 7 or 15 times a square. - Hugo Pfoertner, Aug 13 2017

Links

Table of n, a(n) for n=1..6.

Eike Hertel, Reguläre Dreieckspflasterungen konvexer Polygone, Jenaer Schriften zur Mathematik und Informatik Math/Inf/01/13, 2013 (Preprint).

Eike Hertel, Christian Richter, Tiling Convex Polygons with Congruent Equilateral Triangles, Discrete Comput Geom (2014) 51:753-759.

MathOverflow, Which natural numbers are a square minus a sum of two squares?. Answer by user "Lucia", 2014 Dec 5.

Crossrefs

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

Sequence in context: A193553 A274090 A195041 * A302125 A006188 A198589

Adjacent sequences: A229459 A229460 A229461 * A229463 A229464 A229465

Keyword

nonn,fini,full

Author

Suggested by Eike Hertel, Hugo Pfoertner, Sep 24 2013

Status

approved