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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

Clark Kimberling

STATUS

approved

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Last modified April 24 12:21 EDT 2019. Contains 322429 sequences. (Running on oeis4.)