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A075051 Smallest prime for which the n closest primes are smaller. 7
3, 113, 113, 113, 1327, 1327, 15683, 15683, 248909, 265621, 492113, 492113, 3851459, 7743233, 18640103, 18640103, 18640103, 435917249, 435917249, 435917249, 649580171, 649580171, 19187736221, 19187736221, 19187736221, 94746870541, 94746870541, 673420121333, 1975675658371 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It is surprising that few of the above entries are at the beginning of a prime gap in A000230 or A002386.

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

The smallest prime number for which the three closest primes to itself are all smaller than itself is 113 (the closest primes being 109, 107 and 103). So a(3)=113.

MATHEMATICA

NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; k = 1; Do[ps = Table[0, {n + 1}]; ps = Append[ps, Max[k, 1]]; While[ps = Drop[ps, 1]; ps = Append[ps, NextPrim[ ps[[ -1]]]]; ps[[ -1]] - ps[[ -2]] <= ps[[ -2]] - ps[[1]], ]; Print[ ps[[ -2]]]; k = PrevPrim[ ps[[1]]], {n, 1, 30}]

CROSSREFS

Cf. A001223, A074979, A074982, A075030, A075037, A075038, A075043 & A075050.

Sequence in context: A199640 A221618 A300814 * A139929 A142603 A249164

Adjacent sequences:  A075048 A075049 A075050 * A075052 A075053 A075054

KEYWORD

nonn

AUTHOR

Neil Fernandez, Oct 10 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v, Oct 12 2002

a(23)-a(29) from Donovan Johnson, Jun 19 2008

STATUS

approved

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Last modified April 14 20:07 EDT 2021. Contains 342962 sequences. (Running on oeis4.)