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A139501 Primes of the form x^2 + 21x*y + y^2 for x and y nonnegative. 1
23, 47, 73, 101, 131, 139, 163, 197, 233, 239, 271, 277, 311, 347, 349, 353, 397, 443, 461, 463, 491, 499, 541, 577, 587, 593, 647, 653, 691, 719, 739, 761, 809, 821, 823, 853, 859, 883, 929, 947, 967, 997, 1013, 1051, 1061, 1087, 1151, 1163, 1223, 1277 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..50.

N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

MATHEMATICA

a = {}; w = 21; k = 1; Do[Do[If[PrimeQ[n^2 + w*n*m + k*m^2], AppendTo[a, n^2 + w*n*m + k*m^2]], {n, m, 400}], {m, 1, 400}]; Union[a] (*Artur Jasinski*)

CROSSREFS

Cf. A139489, A007645, A068228, A007519, A033212, A033212, A107152, A107008, A033215, A107145, A139490, A139491.

Sequence in context: A141376 A140614 A001124 * A117876 A090191 A054821

Adjacent sequences:  A139498 A139499 A139500 * A139502 A139503 A139504

KEYWORD

nonn

AUTHOR

Artur Jasinski, Apr 24 2008

STATUS

approved

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Last modified December 4 17:26 EST 2016. Contains 278755 sequences.