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%I #12 Apr 06 2015 10:05:52
%S 2,5,5,5,11,11,11,11,11,11,23,23,23,23,23,23,23,23,23,23,23,23
%N Least prime p such that p+3*k*(k+1) is prime for all k=0,...,n.
%C Inspired by the so-called prime-generating polynomials.
%C 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.
%o (PARI) a(n)=forprime(p=1,,for(i=1,n,ispseudoprime(p+3*(i+1)*i)||next(2));return(p))
%Y Cf. A181963, A181969, A181973, A210626, A211773, A212325, ...
%Y Cf. A005846, A056561.
%Y Cf. A256300, A256301.
%K nonn,more
%O 0,1
%A _M. F. Hasler_, Apr 05 2015