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a(n) = 1 if n is the norm of an Eisenstein prime (see A055664) otherwise 0.
4

%I #7 Dec 06 2017 20:08:16

%S 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 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 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 a(n) = 1 if n is the norm of an Eisenstein prime (see A055664) otherwise 0.

%D L. W. Reid, The Elements of the Theory of Algebraic Numbers, MacMillan, NY, 1910, see Chap. VI.

%H Antti Karttunen, <a href="/A135461/b135461.txt">Table of n, a(n) for n = 0..65537</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%e The smallest primes are 1-omega (of norm 3) and 2 (of norm 4).

%o (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 Cf. A055667, A135462.

%Y Characteristic function of A055664.

%K nonn

%O 0,1

%A _N. J. A. Sloane_, Feb 06 2008