OFFSET
1,2
COMMENTS
Of the first 10000 natural numbers, 4534 are in this sequence, making the density about 45%, quite large! (However, 72491 is not prime; it equals 71*1021, so no multiples of 71 or 1021 are in this sequence.)
LINKS
Eric Chen, Table of n, a(n) for n = 1..4534 (all terms up to 10000)
C. Rivera, Prime producing polynomials
Eric Weisstein's World of Mathematics, Prime-generating polynomial
EXAMPLE
k k^2 + k + 72491
0 72491 = 71*1021
1 72493 (prime)
2 72497 (prime)
3 72503 (prime)
4 72511 = 59*1229
5 72521 = 47*1543
6 72533 (prime)
7 72547 (prime)
8 72563 = 149*487
9 72581 = 181*401
etc.
MAPLE
select(t -> isprime(t^2+t+72491), [$0..100]);
MATHEMATICA
Select[Range[100], PrimeQ[#^2 + # + 72491] &]
PROG
(PARI) v=[ ]; for(n=0, 100, if(isprime(n^2+n+72491), v=concat(v, n), )); v
(Magma) [n: n in [0..100] | IsPrime(n^2 + n + 72491)]; // Vincenzo Librandi, Apr 20 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric Chen, Apr 19 2015
STATUS
approved