OFFSET
1,1
COMMENTS
By Fermat's 4n+1 theorem, q must be congruent to 1 (mod 4).
Corresponding values of k: 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 4, 4, 4, 6, 2, 2, 4, 2. - Zak Seidov, Nov 04 2013
LINKS
Eric W. Weisstein, Fermat's 4n+1 Theorem
EXAMPLE
17 is here because 293 is the first prime after 17^2 and 293 = 17^2 + 2^2.
MATHEMATICA
Select[Prime[Range[200]], IntegerQ[Sqrt[NextPrime[ #^2] - #^2]] & ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 30 2010
EXTENSIONS
Edited and extended by T. D. Noe, May 12 2010
STATUS
approved