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A001479 Let p = A007645(n) be the n-th generalized cuban prime and write p =  x^2 + 3*y^2; a(n) = x.
(Formerly M0166 N0065)
3

%I M0166 N0065

%S 0,2,1,4,2,5,4,7,8,5,2,7,10,1,10,8,2,7,4,13,1,14,8,14,11,7,14,13,16,8,

%T 11,16,17,7,2,19,4,17,19,11,1,14,5,10,22,16,4,23,20,8,23,13,10,5,16,

%U 22,20,19,25,4,11,22,25,8,26,13,1,28,28,26,23,29,28

%N Let p = A007645(n) be the n-th generalized cuban prime and write p = x^2 + 3*y^2; a(n) = x.

%D A. J. C. Cunningham, Quadratic Partitions. Hodgson, London, 1904, p. 1.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%D B. van der Pol and P. Speziali, The primes in k(p). Nederl. Akad. Wetensch. Proc. Ser. A. {54} = Indagationes Math. 13, (1951). 9-15 (1 plate).

%H T. D. Noe, <a href="/A001479/b001479.txt">Table of n, a(n) for n=1..1000</a>

%H S. R. Finch, <a href="http://arXiv.org/abs/math.NT/0701251">Powers of Euler's q-Series</a>, (arXiv:math.NT/0701251).

%t nmax = 56; nextCuban[p_] := If[p1 = NextPrime[p]; Mod[p1, 3] > 1, nextCuban[p1], p1]; cubanPrimes = NestList[ nextCuban, 3, nmax ]; f[p_] := x /. ToRules[ Reduce[x > 0 && y > 0 && p == x^2 + 3*y^2, {x, y}, Integers]]; a[1] = 0; a[n_] := f[cubanPrimes[[n]]]; Table[ a[n] , {n, 1, nmax}] (* _Jean-Fran├žois Alcover_, Oct 19 2011 *)

%o (Haskell)

%o a001479 n = a000196 $ head $

%o filter ((== 1) . a010052) $ map (a007645 n -) $ tail a033428_list

%o -- _Reinhard Zumkeller_, Jul 11 2013

%Y Cf. A001480, A007645.

%Y Cf. A000196, A010052, A033428.

%K nonn,easy,nice

%O 1,2

%A _N. J. A. Sloane_.

%E Definition revised by _N. J. A. Sloane_, Jan 29 2013

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Last modified December 18 06:09 EST 2014. Contains 252079 sequences.