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 A055665 #12 Aug 18 2017 09:44:29
%S A055665 6,6,12,12,12,6,12,12,12,12,12,12,12,12,12,12,6,12,12,12,12,12,12,12,
%T A055665 12,12,12,12,12,12,12,12,6,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
%U A055665 12,12,12,12,6,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12
%N A055665 Number of Eisenstein-Jacobi primes of successive norms (indexed by A055664).
%C A055665 These are the primes in the ring of integers a+b*omega, a and b rational integers, omega = (1+sqrt(-3))/2.
%D A055665 R. K. Guy, Unsolved Problems in Number Theory, A16.
%D A055665 L. W. Reid, The Elements of the Theory of Algebraic Numbers, MacMillan, NY, 1910, see Chap. VI.
%H A055665 Antti Karttunen, <a href="/A055665/b055665.txt">Table of n, a(n) for n = 1..1000</a> (computed from the b-file of A055666 with the formula of _Franklin T. Adams-Watters_)
%F A055665 a(n) = 6 * A055666(n) - _Franklin T. Adams-Watters_, May 05 2006
%e A055665 There are 6 Eisenstein-Jacobi primes of norm 3, omega-omega^2 times one of the 6 units [ +-1, +-omega, +-omega^2 ] but only one up to equivalence.
%t A055665 norms = Join[{3}, Select[Range[1000], (PrimeQ[#] && Mod[#, 6] == 1) || (PrimeQ[Sqrt[#]] && Mod[Sqrt[#], 3] == 2) &]]; r[n_] := Reduce[n == a^2 - a*b + b^2, {a, b}, Integers] // Length; A055665 = r /@ norms (* _Jean-François Alcover_, Oct 24 2013 *)
%Y A055665 Cf. A055664-A055668, A055025-A055029. See A004016 and A035019 for theta series of Eisenstein (or hexagonal) lattice.
%K A055665 nonn,easy,nice
%O A055665 1,1
%A A055665 _N. J. A. Sloane_, Jun 09 2000
%E A055665 More terms from _Franklin T. Adams-Watters_, May 05 2006