A140615 - OEIS

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A140615

Primes of the form 13x^2+6xy+21y^2.

13, 61, 109, 277, 349, 373, 541, 613, 733, 853, 877, 997, 1069, 1117, 1381, 1429, 1597, 1669, 1693, 1789, 1861, 1933, 2053, 2221, 2389, 2437, 2749, 2917, 3109, 3181, 3229, 3253, 3373, 3517, 3541, 3637, 3709, 4021, 4549, 4597, 4813, 4861

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OFFSET

1,1

COMMENTS

Discriminant=-1056. Also primes of the form 13x^2+2xy+61y^2.

In base 12, the sequence is 11, 51, 91, 1E1, 251, 271, 391, 431, 511, 5E1, 611, 6E1, 751, 791, 971, 9E1, E11, E71, E91, 1051, 10E1, 1151, 1231, 1351, 1471, 14E1, 1711, 1831, 1971, 1X11, 1X51, 1X71, 1E51, 2051, 2071, 2131, 2191, 23E1, 2771, 27E1, 2951, 2991, where X is 10 and E is 11. Moreover, the discriminant is -740. - Walter Kehowski, May 31 2008

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)

MATHEMATICA

Union[QuadPrimes2[13, 6, 21, 10000], QuadPrimes2[13, -6, 21, 10000]] (* see A106856 *)

CROSSREFS

Cf. A140633.

Sequence in context: A028874 A087106 A142402 * A086361 A119151 A081589

Adjacent sequences: A140612 A140613 A140614 * A140616 A140617 A140618

KEYWORD

nonn,easy

AUTHOR

T. D. Noe, May 19 2008

STATUS

approved