A070106 Number of integer triangles with perimeter n which are obtuse and isosceles.

0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 4, 4, 3, 3, 4, 4, 3, 4, 4

Offset

1,31

Comments

a(n)=A070101(n)-A024156(n); a(n)=A059169(n)-A070098(n).

Links

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

R. Zumkeller, Integer-sided triangles

Example

For n=11 there are A005044(11)=4 integer triangles: [1,5,5], [2,4,5], [3,3,5] and [3,4,4]; only one of the two obtuses ([2,4,5] and [3,3,5]) is also isosceles; therefore a(11)=1.

Crossrefs

Cf. A070080, A070081, A070082, A059169, A070107, A070108, A070133.

Sequence in context: A328966 A077479 A335225 * A182595 A109706 A174541

Adjacent sequences: A070103 A070104 A070105 * A070107 A070108 A070109

Keyword

nonn

Author

Reinhard Zumkeller, May 05 2002

Status

approved