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A052334 Record primes reached in A052333. 5
3, 5, 7, 19, 31, 43, 103, 223, 367, 463, 5503, 738197503 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Start with n=1, take 2n+1, if composite take 2n+1 again, keep going until you reach a prime. Repeat for n=2, 3... If prime is a record, add to sequence. If never reach a prime, skip that value of n.

LINKS

Table of n, a(n) for n=1..12.

MATHEMATICA

record = 2; Reap[For[n = 1, n <= 100, n++, k = n; While[ !PrimeQ[k = 2*k + 1]]; If[k > record, Print[k]; Sow[k]; record = k]]][[2, 1]] (* Jean-François Alcover, Jul 19 2013 *)

CROSSREFS

Cf. A050412, A051914, A052333, A052339, A052340.

Sequence in context: A179687 A106919 A005850 * A322302 A154526 A126144

Adjacent sequences:  A052331 A052332 A052333 * A052335 A052336 A052337

KEYWORD

nonn,nice

AUTHOR

Christian G. Bower, Dec 19 1999

EXTENSIONS

Next term is a 771-digit prime reached after 2552 iterations starting from 73 - Warut Roonguthai. This was proved to be a prime by Paul Jobling (Paul.Jobling(AT)WhiteCross.com) using PrimeForm and by Ignacio Larrosa Cañestro using Titanix (http://www.znz.freesurf.fr/pages/titanix.html). [Oct 30 2000]

STATUS

approved

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Last modified July 23 20:32 EDT 2019. Contains 325264 sequences. (Running on oeis4.)