OFFSET
1,1
COMMENTS
This is a special case of prime chains generated by f(x) = cx + d.
a(11) > 8695354111. - Donovan Johnson, Sep 27 2008
LINKS
D. H. Lehmer, On certain chains of primes, Proc. London Math. Soc. (3) 14a 1965 183-186.
EXAMPLE
a(3) = 3 since 3, f(3) = 13 and f(13) = 43 are primes when f(x) = 3*x + 4.
MATHEMATICA
c[p_] := Block[{k=1, q=3*p + 4}, While[PrimeQ[q], q=3*q+4; k++]; k]; a[n_] := Block[{p = 2}, While[c[p] < n, p = NextPrime[p]]; p]; Array[a, 7] (* Giovanni Resta, Mar 22 2017 *)
CROSSREFS
KEYWORD
more,nonn
AUTHOR
W. Edwin Clark, Jun 14 2003
EXTENSIONS
a(9)-a(10) from Donovan Johnson, Sep 27 2008
a(11)-a(12) from John Cerkan, Jan 13 2017
a(13)-a(14) from Giovanni Resta, Mar 22 2017
STATUS
approved