OFFSET
1,1
REFERENCES
David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, p. 103.
FORMULA
For squarefree n >= 2, list n if n=1 mod 4 else 4n.
MAPLE
with(numtheory): a:= proc(n) if issqrfree(n) then RETURN(piecewise(n mod 4=1, n, 4*n)) else RETURN(NULL) fi: end: seq(a(n), n=2..150); # C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005
MATHEMATICA
Reap[For[n = 2, n <= 100, n++, If[SquareFreeQ[n], Sow[If[Mod[n, 4] == 1, n, 4 n]]]]][[2, 1]] (* Jean-François Alcover, Mar 22 2023 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005
STATUS
approved