OFFSET
1,1
COMMENTS
A positive integer N is in the sequence if and only if there exist positive rational numbers x,y such that x*y>1 and 4*x*y*(x+y)/(x*y-1)=N.
Except for N=27, a positive integer N is in this sequence if and only if N>20 and the elliptic curve w^2 = u^3 + N^2*(u+64)^2 has positive rank.
CROSSREFS
KEYWORD
nonn
AUTHOR
Thomas Bokk, Nov 05 2015
STATUS
approved