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A104138 Smallest prime followed by n or more composites. 2
2, 3, 7, 7, 23, 23, 89, 89, 113, 113, 113, 113, 113, 113, 523, 523, 523, 523, 887, 887, 1129, 1129, 1327, 1327, 1327, 1327, 1327, 1327, 1327, 1327, 1327, 1327, 1327, 1327, 9551, 9551, 15683, 15683, 15683, 15683, 15683, 15683, 15683, 15683, 19609 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Except for a(1), records occur at even values of n, and each term appears an even number of times consecutively. (Proof. A maximal run of composites must begin and end at even numbers.) - Jonathan Sondow, May 31 2014

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 0..1000

FORMULA

Record prime A002386(n+1) appears A053695(n-1) times, for n>1.

a(n) = A030296(n) - 1, for n > 0. - Jonathan Sondow, May 31 2014

EXAMPLE

a(10)=113 because it is the first prime occurring before primes 199,211,293,317,467,509,... all followed by at least ten successive composites.

CROSSREFS

Cf. A002386, A005250, A030296, A053695.

Sequence in context: A276730 A179894 A027672 * A281909 A083809 A092967

Adjacent sequences:  A104135 A104136 A104137 * A104139 A104140 A104141

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Mar 07 2005

EXTENSIONS

a(34) corrected by Charles R Greathouse IV, Aug 09 2011

STATUS

approved

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Last modified June 24 15:07 EDT 2017. Contains 288697 sequences.