

A052334


Record primes reached in A052333.


6



3, 5, 7, 19, 31, 43, 103, 223, 367, 463, 5503, 738197503
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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.
a(13) is a 771digit 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]


LINKS



FORMULA



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]] (* JeanFrançois Alcover, Jul 19 2013 *)


CROSSREFS



KEYWORD

nonn,nice


AUTHOR



STATUS

approved



