A070208 Number of integer triangles with perimeter n having integral area but not integral inradius.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 2, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2

Offset

1,36

Comments

a(n) = A051516(n) - A070201(n).

References

Mohammad K. Azarian, Circumradius and Inradius, Problem S125, Math Horizons, Vol. 15, Issue 4, April 2008, p. 32. Solution published in Vol. 16, Issue 2, November 2008, p. 32.

Links

Table of n, a(n) for n=1..90.

Eric Weisstein's World of Mathematics, Incircle.

Eric Weisstein's World of Mathematics, Heron's Formula.

R. Zumkeller, Integer-sided triangles

Crossrefs

Sequence in context: A028710 A178926 A028637 * A028629 A047751 A028706

Adjacent sequences: A070205 A070206 A070207 * A070209 A070210 A070211

Keyword

nonn

Author

Reinhard Zumkeller, May 05 2002

Status

approved