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 A023509 Greatest prime divisor of prime(n) + 1. 12
 3, 2, 3, 2, 3, 7, 3, 5, 3, 5, 2, 19, 7, 11, 3, 3, 5, 31, 17, 3, 37, 5, 7, 5, 7, 17, 13, 3, 11, 19, 2, 11, 23, 7, 5, 19, 79, 41, 7, 29, 5, 13, 3, 97, 11, 5, 53, 7, 19, 23, 13, 5, 11, 7, 43, 11, 5, 17, 139, 47, 71, 7, 11, 13, 157, 53, 83, 13, 29, 7, 59, 5, 23, 17, 19, 3, 13 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A006530(A008864(n)). - R. J. Mathar, Feb 06 2019 MATHEMATICA Table[FactorInteger[Prime[n] + 1][[-1, 1]], {n, 100}] PROG (PARI) A023509(n) = {local(f); f=factor(prime(n)+1); f[matsize(f)[1], 1]} \\ Michael B. Porter, Feb 02 2010 CROSSREFS Sequence in context: A018837 A097618 A039639 * A115041 A039641 A198729 Adjacent sequences:  A023506 A023507 A023508 * A023510 A023511 A023512 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 29 20:22 EDT 2020. Contains 337432 sequences. (Running on oeis4.)