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 A135461 #11 Apr 15 2025 11:58:54 %S A135461 0,0,0,1,1,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0, %T A135461 0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1, %U A135461 0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0 %N A135461 a(n) = 1 if n is the norm of an Eisenstein prime (see A055664) otherwise 0. %D A135461 L. W. Reid, The Elements of the Theory of Algebraic Numbers, MacMillan, NY, 1910, see Chap. VI. %H A135461 Antti Karttunen, <a href="/A135461/b135461.txt">Table of n, a(n) for n = 0..65537</a> %H A135461 <a href="/index/Ch#char_fns">Index entries for characteristic functions</a> %e A135461 The smallest primes are 1-omega (of norm 3) and 2 (of norm 4). %t A135461 f[n_]:=If[ PrimeQ[n] && Mod[n, 6] == 1|| PrimeQ[Sqrt[n]] && Mod[Sqrt[n], 3] == 2||n==3,1,0];Array[f,99,0] (* _James C. McMahon_, Apr 15 2025 *) %o A135461 (PARI) A135461(n) = (isprime(n) && n%3<2) || (issquare(n, &n) && isprime(n) && n%3==2); \\ This is _Charles R Greathouse IV_'s Apr 30 2013 code (with name "is") for A055664. - _Antti Karttunen_, Dec 06 2017 %Y A135461 Cf. A055667, A135462. %Y A135461 Characteristic function of A055664. %K A135461 nonn %O A135461 0,1 %A A135461 _N. J. A. Sloane_, Feb 06 2008