OFFSET
1,1
REFERENCES
Harvey Cohn, Advanced Number Theory, Dover Publications, New York, N.Y. (1980).
S Vidhyalakshmi, V Krithika, K Agalya, On The Negative Pell Equation, International Journal of Emerging Technologies in Engineering Research (IJETER), Volume 4, Issue 2, February (2016) www.ijeter.everscience.org,
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 500 terms from Robert Israel)
MAPLE
filter:= t -> not numtheory:-issqrfree(t) and [isolve(x^2 - t*y^2 = -1)]<>[]:
select(filter, [$1..10000]); # Robert Israel, Jul 10 2018
MATHEMATICA
r[n_] := Reduce[x>0 && y>0 && x^2 - n y^2 == -1, {x, y}, Integers];
Reap[For[n = 1, n <= 5000, n++, If[!SquareFreeQ[n], If[r[n] =!= False, Print[n]; Sow[n]]]]][[2, 1]] (* Jean-François Alcover, Mar 05 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset changed by Robert Israel, Jul 10 2018
STATUS
approved