proposed
approved
proposed
approved
editing
proposed
a(4)=9, as the 4th PPT is generated from the 9th term of the triangular array at index (3,4). This gives (x,y) as (3,4) and it generates the PPT (7,24,25). Conversely the PPT (7,24,25) gives (x,y) = (Sqrtsqrt((25-7)/2),Sqrt sqrt((25+7)/2)=(3,4). It is the 9th term of the triangular array and the 4th term of the enumerating sequence.
approved
editing
Frank M Jackson, <a href="/A243808/b243808_1.txt">Table of n, a(n) for n = 1..57</a>
editing
approved
Frank M Jackson, <a href="/A243808/b243808_1.txt">Table of n, a(n) for n = 1..57</a>
approved
editing
proposed
approved
editing
proposed
Lance Fortnow, <a href="http://blog.computationalcomplexity.org/2004/03/counting-rationals-quickly.html">Counting the Rationals Quickly</a>, Computational Complexity Weblog, Monday, March 01, 2004.
Yoram Sagher, <a href="http://www.jstor.org/stable/2324846">Counting the rationals</a>, Amer. Math. Monthly, 96 (1989), p. 823. Math. Rev. 90i:04001.
approved
editing
editing
approved