A084954 Smallest initial prime of a prime chain of length n under the iteration x->2x+3.

2, 2, 2, 2, 47, 47, 6047, 477727, 30596497, 3388516667, 340746580567, 1763093883977, 773521306107547, 1142275515892937, 391230854658184967

Offset

1,1

Comments

This is a special case of prime chains generated by f(x) = cx + d.

Is it smallest initial prime of a prime chain of length n under the iteration x->2x+3, or not? At least up to 3388516667 it is the smallest one. - Zak Seidov, Dec 20 2013

Links

Table of n, a(n) for n=1..15.

D. H. Lehmer, On certain chains of primes, Proc. London Math. Soc. (3) 14a 1965 183-186.

Example

a(3) = 2 since 2, 2*2+3=7 and 2*7+3=17 are primes.

Crossrefs

Cf. A057330, A057331, A083388, A084955, A084956, A084957, A084958, A084959, A084960, A084961, A128509, A134701, A134702.

Sequence in context: A378134 A154288 A225057 * A226281 A217993 A049300

Adjacent sequences: A084951 A084952 A084953 * A084955 A084956 A084957

Keyword

nonn,more

Author

W. Edwin Clark, Jun 14 2003

Extensions

More terms from Don Reble, Nov 07 2007

a(15) from Bert Dobbelaere, Jun 01 2025

Name clarified by Sean A. Irvine, May 22 2026

Status

approved