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 A256302 Least prime p such that p+3*k*(k+1) is prime for all k=0,...,n. 1
 2, 5, 5, 5, 11, 11, 11, 11, 11, 11, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified April 22 01:34 EDT 2024. Contains 371887 sequences. (Running on oeis4.)