OFFSET
1,3
FORMULA
Two prime Gaussian integers are not counted separately if they are associated, i.e. if their quotient is a unit (1, i, -1 or -i).
Similar to the ordinary prime number theorem (see A000720) we have the asymptotic expression: a(n) ~ n^2/(2 * log(n)) - Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 16 2001
MATHEMATICA
m = 50;
t = Table[x + y I, {x, -m, m}, {y, -m, m}] // Flatten[#, 1]& // Select[#, PrimeQ[#, GaussianIntegers -> True]& ]& // Sort // DeleteDuplicates[#, Abs[#1] == Abs[#2] && MatchQ[#1 /#2 , 1|-1|I|-I]& ]&;
a[n_] := Select[t, Abs[#] <= n&] // Length;
Array[a, m] (* Jean-François Alcover, Jul 29 2016 *)
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
Reiner Martin, Jul 14 2001
STATUS
approved