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%I #11 Oct 29 2022 10:20:28
%S 2,3,5,11,13,23,29,37,43,47,59,61,67,73,83,103,107,113,131,137,139,
%T 149,157,167,173,179,193,211,223,227,229,233,263,269,277,281,283,293,
%U 311,313,317,331,347,353,359,367,373,383,389,397,409,421,439,443,457,467
%N Primes P such that P < (largest prime factor of (P-1)) * (largest prime factor of (P+1)).
%e For n = 3, a(3)=11.
%e The prime P = 11
%e P-1 = 10 (largest prime factor of 10 is 5)
%e P+1 = 12 (largest prime factor of 12 is 3)
%e 11 < 5*3.
%t Select[Prime[Range[100]],#<(FactorInteger[#-1][[-1,1]] FactorInteger[#+1][[-1,1]])&] (* _Harvey P. Dale_, Feb 22 2011 *)
%o (PARI) isok(p) = (p==2) || (isprime(p) && (p < vecmax(factor(p-1)[, 1]) * vecmax(factor(p+1)[, 1]))); \\ _Michel Marcus_, Oct 29 2022
%Y Cf. A180641. See also A103666, A103667.
%K nonn
%O 1,1
%A _Karl Hovekamp_, Sep 14 2010
%E Initial term, i.e., 2, added by _Harvey P. Dale_, Feb 22 2011
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