This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A055673 #17 Aug 06 2021 01:57:34
%S A055673 2,7,9,17,23,25,31,41,47,71,73,79,89,97,103,113,121,127,137,151,167,
%T A055673 169,191,193,199,223,233,239,241,257,263,271,281,311,313,337,353,359,
%U A055673 361,367,383,401,409,431,433,439,449,457,463,479,487,503,521,569,577,593
%N A055673 Absolute values of norms of primes in ring of integers Z[sqrt(2)].
%C A055673 The integers have the form z = a + b*sqrt(2), a and b rational integers. The norm of z is a^2 - 2*b^2, which may be negative.
%D A055673 L. W. Reid, The Elements of the Theory of Algebraic Numbers, MacMillan, NY, 1910, see Chap. VII.
%H A055673 T. D. Noe, <a href="/A055673/b055673.txt">Table of n, a(n) for n = 1..1000</a>
%F A055673 Consists of 2; rational primes = +-1 (mod 8); and squares of rational primes = +-3 (mod 8).
%t A055673 maxNorm = 593; s1 = Select[Range[-1, maxNorm, 8], PrimeQ]; s2 = Select[Range[1, maxNorm, 8], PrimeQ]; s3 = Select[Range[-3, Sqrt[maxNorm], 8], PrimeQ]^2; s4 = Select[Range[3, Sqrt[maxNorm], 8], PrimeQ]^2; Union[{2}, s1, s2, s3, s4] (* _Jean-François Alcover_, Dec 07 2012, from formula *)
%o A055673 (PARI) is(n)=!!if(isprime(n), setsearch([1,2,7],n%8), issquare(n,&n) && isprime(n) && setsearch([3,5], n%8)) \\ _Charles R Greathouse IV_, Sep 10 2016
%Y A055673 Cf. A055026-A055029, A055669-A055672, A118916, A118917.
%K A055673 nonn,easy,nice
%O A055673 1,1
%A A055673 _N. J. A. Sloane_, Jun 09 2000
%E A055673 I would also like to get the sequences (analogous to A055027 and A055029) giving the number of inequivalent primes mod units. Of course now there are infinitely many units.
%E A055673 More terms from _Franklin T. Adams-Watters_, May 05 2006