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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)
10
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

E. F. Ecklund and R. B. Eggleton, Prime factors of consecutive integers, Amer. Math. Monthly, 79 (1972), 1082-1089.

D. H. Lehmer, On a problem of Stormer, Ill. J. Math., 8 (1964), 57-69.

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, Størmer'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

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Last modified December 19 19:11 EST 2014. Contains 252239 sequences.