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A106908
Primes of the form 4x^2+3xy+4y^2, with x and y any integer.
1
5, 11, 31, 89, 179, 181, 191, 331, 401, 419, 421, 449, 521, 599, 619, 641, 709, 719, 829, 859, 911, 971, 991, 1021, 1039, 1109, 1259, 1291, 1301, 1489, 1511, 1549, 1621, 1709, 1831, 1871, 1879, 2011, 2039, 2099, 2161, 2179, 2281, 2311, 2381
OFFSET
1,1
COMMENTS
Discriminant=-55.
Primes p such that x^4 - 2x^3 + x - 1 has no integer roots modulo p^2. According to the Bunyakovsky conjecture, there are infinitely many such primes. - Griffin N. Macris, Jul 21 2016
LINKS
Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
EXAMPLE
89 is in the sequence since it is prime and with x=5 and y=-1, 4x^2 + 3xy + 4y^2 = 4*5^2 + 3*5*(-1) + 4*(-1)^2 = 100 - 15 + 4 = 89. - Michael B. Porter, Jul 22 2016
MAPLE
N:= 10000: # to get all terms <= N
S:= {}:
for y from 0 to floor(sqrt(16*N/55)) do
s:= floor(sqrt(16*N-55*y^2));
S:= S union select(isprime, {seq(4*x^2 + 3*x*y + 4*y^2,
x = ceil((-s-3*y)/8) .. floor((s-3*y)/8))})
od:
sort(convert(S, list)); # Robert Israel, Jul 21 2016
MATHEMATICA
Union[QuadPrimes2[4, 3, 4, 10000], QuadPrimes2[4, -3, 4, 10000]] (* see A106856 *)
CROSSREFS
Sequence in context: A023276 A074648 A236428 * A107442 A349611 A323867
KEYWORD
nonn,easy
AUTHOR
T. D. Noe, May 09 2005
STATUS
approved