

A056907


Numbers k such that 36*k^2 + 12*k + 5 is prime (sorted by absolute values with negatives before positives).


2



0, 1, 1, 2, 3, 6, 6, 8, 11, 11, 12, 14, 16, 16, 17, 19, 21, 23, 26, 27, 28, 32, 34, 36, 36, 39, 39, 41, 42, 44, 46, 46, 48, 49, 51, 52, 53, 58, 62, 64, 67, 68, 71, 71, 76, 77, 79, 81, 84, 89, 91, 96, 99, 101, 101, 102, 104, 111, 111, 113
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OFFSET

0,4


COMMENTS

36*k^2 + 12*k + 5 = (6*k+1)^2 + 4, which is four more than a square. Except for a(0), a(n) is never a multiple of 5.


LINKS

Table of n, a(n) for n=0..59.


EXAMPLE

a(3)=2 since 36*2^2 + 12*2 + 5 = 173 which is prime (as well as being four more than a square).


CROSSREFS

This sequence and formula, together with A056908 and its formula, generate all primes of the form k^2+4, i.e., A005473. Except for the first term, this sequence is a subsequence of A047201. Cf. A056900, A056902, A056904, A056906.
Sequence in context: A080235 A198516 A187326 * A039799 A185423 A144583
Adjacent sequences: A056904 A056905 A056906 * A056908 A056909 A056910


KEYWORD

sign


AUTHOR

Henry Bottomley, Jul 07 2000


STATUS

approved



