OFFSET
1,1
COMMENTS
This sequence consists of the primes p (not 5, 13, or 37) such that p == 1, 3 or 5 (mod 8). The density of these primes is 0.75. - T. D. Noe, May 21 2004
Primes of the form a^2 + b^2 + c^2 with 1 <= a <= b <= c. - Zak Seidov, Nov 08 2013
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
101 is a term since 101 = 64 + 36 + 1 = 8^2 + 6^2 + 1^2.
MATHEMATICA
lst={}; lim=32; Do[n=a^2+b^2+c^2; If[n<lim^2 && PrimeQ[n], lst=Union[lst, {n}]], {a, lim}, {b, a, Sqrt[lim^2-a^2]}, {c, b, Sqrt[lim^2-a^2-b^2]}]; lst
With[{nn=30}, Select[Union[Total/@Tuples[Range[nn]^2, 3]], PrimeQ[#]&& #<= nn^2+2&]] (* Harvey P. Dale, Jun 18 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 01 2003
STATUS
approved