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A057713 Smallest prime divisor of Kummer numbers ( = primorials - 1). 6
1, 5, 29, 11, 2309, 30029, 61, 53, 37, 79, 228737, 229, 304250263527209, 141269, 191, 87337, 27600124633, 1193, 163, 260681003321, 313, 163, 139, 23768741896345550770650537601358309, 66683, 2990092035859, 15649, 17515703, 719, 295201, 15098753, 10172884549, 20962699238647, 4871, 673, 311, 1409, 1291, 331, 1450184819, 23497, 711427, 521, 673, 519577, 1372062943, 56543, 811, 182309, 53077, 641, 349, 389 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..53.

M. Kraitchik, On the divisibility of factorials, Scripta Math., 14 (1948), 24-26 (but beware errors). [Annotated scanned copy]

R. Mestrovic, Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof, arXiv preprint arXiv:1202.3670 [math.HO], 2012 - N. J. A. Sloane, Jun 13 2012

Hisanori Mishima, Factorizations of many number sequences

R. G. Wilson v, Explicit factorizations

EXAMPLE

6th term in the sequence corresponds to 7th primorial=510510 and 510509=61.8369, so a(7)=61

MATHEMATICA

Map[If[PrimeQ@ #, #, FactorInteger[#][[1, 1]]] &, FoldList[#1 #2 &, Prime@ Range@ 36] - 1] (* Michael De Vlieger, Feb 18 2017 *)

CROSSREFS

Cf. A002110, A057588, A002585, A006862, A002584.

Sequence in context: A033503 A181616 A057206 * A124987 A002584 A001990

Adjacent sequences:  A057710 A057711 A057712 * A057714 A057715 A057716

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 25 2000

EXTENSIONS

More terms from Klaus Brockhaus, Larry Reeves (larryr(AT)acm.org) and Robert G. Wilson v, Apr 02 2001

STATUS

approved

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Last modified June 20 00:47 EDT 2019. Contains 324223 sequences. (Running on oeis4.)