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 A084959 Initial prime of a prime chain of length n under the iteration x->5x+6. 6
 2, 5, 7, 7, 79, 79, 345431, 21171649, 34640153, 4174239239, 268130051191, 268130051191, 253134809926049, 253134809926049, 253134809926049 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This is a special case of prime chains generated by f(x) = cx + d. a(11) > 8695354111. [From Donovan Johnson, Sep 27 2008] REFERENCES D. H. Lehmer, On certain chains of primes, Proc. London Math. Soc. (3) 14a 1965 183-186. LINKS EXAMPLE a(3) = 13 since 7, f(7) = 41, and f(41) = 211 are primes when f(x) = 5*x + 6. MATHEMATICA c[p_] := Block[{k=1, q = 5*p+6}, While[PrimeQ[q], q = 5*q+6; k++]; k]; a[n_] := Block[{p = 2}, While[c[p] < n, p = NextPrime[p]]; p]; Array[a, 7] (* Giovanni Resta, Mar 22 2017 *) CROSSREFS Cf. A057330, A057331, A083388, A084954, A084955, A084956, A084957, A084958, A084960, A084961. Sequence in context: A120303 A093413 A004099 * A021799 A154848 A195997 Adjacent sequences:  A084956 A084957 A084958 * A084960 A084961 A084962 KEYWORD more,nonn AUTHOR W. Edwin Clark, Jun 14 2003 EXTENSIONS a(7) corrected and a(8)-a(10) from Donovan Johnson, Sep 27 2008 a(11)-a(12) from John Cerkan, Jan 11 2017 a(13)-a(15) from Giovanni Resta, Mar 22 2017 STATUS approved

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Last modified October 21 21:50 EDT 2018. Contains 316429 sequences. (Running on oeis4.)