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A084955
Initial prime of a prime chain of length n under the iteration x->2x+5.
7
2, 3, 7, 13, 13, 13, 541, 4594309, 64649503, 7577449963, 2005324830163, 39676048812109, 272235769110157, 494535766350049
OFFSET
1,1
COMMENTS
This is a special case of prime chains generated by f(x) = cx + d.
LINKS
D. H. Lehmer, On certain chains of primes, Proc. London Math. Soc. (3) 14a 1965 183-186.
EXAMPLE
a(3)=7 since 7, 2*7+5=19 and 2*19+5=43 are primes.
CROSSREFS
Cf. A084954.
Sequence in context: A225093 A278007 A081256 * A273056 A026472 A286176
KEYWORD
nonn,more
AUTHOR
W. Edwin Clark, Jun 14 2003
EXTENSIONS
More terms from Don Reble, Nov 07 2007
STATUS
approved