Under construction
 Wat mij zoal bezighoudt
 Rational numbers and geometric configurations.
 Herontriangles.
 Congruent numbers.
 Regular polytopes.
 Number fields.
 Publications

Qquadrangles inscribed in a cirkle. (14 jul 2014)

Capita Qconfigurations. (27 okt 2014)

Qcapita on the arbelos. (7 jul 2015)

A180622 (24game) Number of distinct sums i+j, absolute differences ij, products ij and quotients i/j and j/i with 1 <= i, j <= n. (12 sep 2010) Extensions by R.J. Mathar (19 sep 2010).

A337140 Numbers n = a + b with a and b positive integers such that their product a*b = k^2 is a square. (18 aug 2020)

Heron Trilaterals / Bhaskara Equations / Continued Fractions / I. (1 okt 2020)

A338939 a(n) is the number of partitions n = a + b such that a*b is a perfect square. (16 nov 2020)

A338940 a(n) is the number of solutions of the Diophantine equation p x * (x + n) = y^2 with p = a*b is a perfect square and a+b = n. (16 nov 2020)

The number of Heron triangles that match a 'finite' partition of a side with lenght n.