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A070106 Number of integer triangles with perimeter n which are obtuse and isosceles. 5
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 15 00:36 EDT 2020. Contains 335762 sequences. (Running on oeis4.)