OFFSET
1,36
COMMENTS
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..5000
Mohammad K. Azarian, Solution to Problem S125: Circumradius and Inradius, Math Horizons, Vol. 16, Issue 2, November 2008, p. 32.
Eric Weisstein's World of Mathematics, Incircle.
Eric Weisstein's World of Mathematics, Heron's Formula.
Reinhard Zumkeller, Integer-sided triangles
EXAMPLE
PROG
(Ruby)
def A(n)
cnt = 0
(1..n / 3).each{|a|
(a..(n - a) / 2).each{|b|
c = n - a - b
if a + b > c
s = n / 2r
t = (s - a) * (s - b) * (s - c) / s
if t.denominator == 1
t = t.to_i
cnt += 1 if Math.sqrt(t).to_i ** 2 == t
end
end
}
}
cnt
end
def A070201(n)
(1..n).map{|i| A(i)}
end
p A070201(100) # Seiichi Manyama, Oct 06 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 05 2002
STATUS
approved