login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A128968
a(n) is the n-th prime of the form x^2+n.
0
2, 3, 19, 53, 2309, 967, 151, 6569, 3373, 2819, 15887, 2221, 3613, 81239, 4639, 6257, 101141, 6907, 35363, 106949, 59557, 6911, 49307, 70249, 10429, 408347, 33151, 9437, 518429, 63031, 40031, 159233, 155269, 66083, 725939, 156061, 13033, 641639
OFFSET
1,1
EXAMPLE
a(4)=53 because 5=1^2+4,13=3^2+4, 29=5^2+4, 53=7^2+4 are prime and 53 is the 4th such prime.
MATHEMATICA
Table[Select[Range[0, 1000]^2+n, PrimeQ][[n]], {n, 40}] (* Harvey P. Dale, Aug 30 2016 *)
CROSSREFS
Sequence in context: A248702 A171149 A157042 * A153409 A143893 A262957
KEYWORD
nonn
AUTHOR
John L. Drost, Apr 28 2007
STATUS
approved