A256302 Least prime p such that p+3*k*(k+1) is prime for all k=0,...,n.

2, 5, 5, 5, 11, 11, 11, 11, 11, 11, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23

Offset

0,1

Comments

Inspired by the so-called prime-generating polynomials.

Since p | 3n(n+1) for n=p-1, one has a(n) > p(n). Otherwise stated, a(p-1) = p (as, e.g., for p=23) is optimal.

Links

Table of n, a(n) for n=0..21.

Prog

(PARI) a(n)=forprime(p=1, , for(i=1, n, ispseudoprime(p+3*(i+1)*i)||next(2)); return(p))

Crossrefs

Cf. A181963, A181969, A181973, A210626, A211773, A212325, ...

Cf. A005846, A056561.

Cf. A256300, A256301.

Sequence in context: A200683 A286541 A078576 * A205396 A082086 A082084

Adjacent sequences: A256299 A256300 A256301 * A256303 A256304 A256305

Keyword

nonn,more

Author

M. F. Hasler, Apr 05 2015

Status

approved