The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A140615 Primes of the form 13x^2+6xy+21y^2. 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 (list; graph; refs; listen; history; text; internal format)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 13 17:30 EDT 2021. Contains 342936 sequences. (Running on oeis4.)