OFFSET
1,1
COMMENTS
The triples (a, b, c) are displayed in increasing order of side a, and if sides a coincide then in increasing order of the side b.
The sequence is not increasing because a(4) = 35 > a(5) = 28, but, these sides c are listed in increasing order in A020886.
For the corresponding primitive triples and miscellaneous properties and references, see A343891.
FORMULA
a(n) = A343891(n, 3).
EXAMPLE
a(3) = 20, because the third triple is (15, 12, 20) with side c = 20, satisfying 1/20 = 2/15 - 1/12 and 15-12 < 20 < 15+12.
MAPLE
for a from 4 to 200 do
for b from floor(a/2)+1 to a-1 do
c := a*b/(2*b-a);
if c=floor(c) and igcd(a, b, c)=1 and c-b<a then print(c); end if;
end do;
end do;
CROSSREFS
KEYWORD
nonn
AUTHOR
Bernard Schott, May 06 2021
STATUS
approved