

A002072


a(n) = smallest number m such that for all i>m, either i or i+1 has a prime factor > prime(n).
(Formerly M4560 N1942)


9



1, 8, 80, 4374, 9800, 123200, 336140, 11859210, 11859210, 177182720, 1611308699, 3463199999, 63927525375, 421138799639, 1109496723125, 1453579866024, 20628591204480, 31887350832896, 31887350832896, 119089041053696, 2286831727304144, 9591468737351909375, 9591468737351909375, 9591468737351909375, 9591468737351909375, 9591468737351909375, 19316158377073923834000
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OFFSET

1,2


REFERENCES

E. F. Ecklund and R. B. Eggleton, Prime factors of consecutive integers, Amer. Math. Monthly, 79 (1972), 10821089.
D. H. Lehmer, On a problem of Stormer, Ill. J. Math., 8 (1964), 5769.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..27.
Don Reble, Python program
Wikipedia, Stormer's Theorem
Jim White, Results to P = 173


EXAMPLE

31887350832897=3^9*7*37*41^2*61^2, 31887350832896=2^8*13*19*23*29^4*31, this number appears twice because there is no pair of numbers with max. factor = 67 that is larger than this number.


PROG

Program in C written by R. Gerbicz, modified by Fred Schneider and Jim White.


CROSSREFS

Cf. A002071, A003032, A003033, A122463, A145606, A175607. Equals A117581(n)  1.
Sequence in context: A222671 A240325 A145606 * A193943 A067449 A078292
Adjacent sequences: A002069 A002070 A002071 * A002073 A002074 A002075


KEYWORD

nonn,nice


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Don Reble (djr(AT)nk.ca), Jan 11 2005
a(18)a(26) from Fred Schneider, Sep 09 2006
Corrected and extended by Andrey V. Kulsha, Aug 10 2011, according to Jim White's computations


STATUS

approved



