OFFSET
1,1
EXAMPLE
For n = 3, a(3)=11.
The prime P = 11
P-1 = 10 (largest prime factor of 10 is 5)
P+1 = 12 (largest prime factor of 12 is 3)
11 < 5*3.
MATHEMATICA
Select[Prime[Range[100]], #<(FactorInteger[#-1][[-1, 1]] FactorInteger[#+1][[-1, 1]])&] (* Harvey P. Dale, Feb 22 2011 *)
PROG
(PARI) isok(p) = (p==2) || (isprime(p) && (p < vecmax(factor(p-1)[, 1]) * vecmax(factor(p+1)[, 1]))); \\ Michel Marcus, Oct 29 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Karl Hovekamp, Sep 14 2010
EXTENSIONS
Initial term, i.e., 2, added by Harvey P. Dale, Feb 22 2011
STATUS
approved