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A053673 Least number > 1 coprime to n, n+1, n+2, n+3 and n+4. 3
7, 7, 11, 11, 11, 11, 13, 7, 7, 17, 17, 11, 11, 11, 7, 7, 11, 13, 13, 13, 13, 7, 7, 11, 11, 11, 11, 11, 7, 7, 13, 13, 13, 11, 11, 7, 7, 11, 11, 13, 13, 13, 7, 7, 11, 11, 11, 11, 11, 7, 7, 17, 13, 13, 13, 11, 7, 7, 11, 11, 11, 17, 17, 7, 7, 13, 11, 11, 11, 11, 7, 7, 13, 17, 17, 17, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

From Robert Israel, Jul 06 2016: (Start)

Least prime that does not divide n(n+1)(n+2)(n+3)(n+4).

All terms are primes >= 7.

First occurrences of the first few values:

  a(1) = 7, a(3) = 11, a(7) = 13, a(10) = 17, a(117) = 19, a(152) = 23, a(1309) = 29, a(986) = 31, a(1767) = 37, a(203201) = 41, a(868868) = 43

(End)

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MAPLE

f:= proc(n) local p;

  p:= 7;

  while min([n, n+1, n+2, n+3, n+4] mod p) = 0 do p:= nextprime(p) od:

  p

end proc:

seq(f(n), n=1..100); # Robert Israel, Jul 06 2016

MATHEMATICA

Table[k=2; While[First[Union[CoprimeQ[k, #]&/@(n+Range[0, 4])]]== False, k++]; k, {n, 80}] (* Harvey P. Dale, Jul 07 2011 *)

PROG

(Haskell)

import Data.List (elemIndex)

import Data.Maybe (fromJust)

a053673 n = 2 + fromJust

   (elemIndex 1 $ map (gcd $ foldl1 lcm $ take 5 [n..]) [2..])

-- Reinhard Zumkeller, Sep 25 2011

CROSSREFS

Cf. A053669-A053674.

Sequence in context: A084513 A084523 A213886 * A204910 A152672 A003883

Adjacent sequences:  A053670 A053671 A053672 * A053674 A053675 A053676

KEYWORD

nonn,easy,nice

AUTHOR

Henry Bottomley, Feb 15 2000

EXTENSIONS

More terms from Andrew Gacek (andrew(AT)dgi.net), Feb 21 2000 and James A. Sellers, Feb 22 2000

STATUS

approved

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Last modified April 19 01:29 EDT 2019. Contains 322237 sequences. (Running on oeis4.)