A124262 a(n) is the largest prime < 10*a(n-1) for n > 1, with a(1) = 2.

2, 19, 181, 1801, 17989, 179849, 1798487, 17984833, 179848309, 1798483067, 17984830667, 179848306667, 1798483066669, 17984830666651, 179848306666507, 1798483066665031, 17984830666650269, 179848306666502647, 1798483066665026389, 17984830666650263887, 179848306666502638867

Offset: 1

Author

Artur Jasinski, Dec 16 2006

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..1000, extending and correcting a b-file from Artur Jasinski

Crossrefs

Cf. A126031, A126041, A124475.

Sequences for other powers of 10: A124339 (100), A124361 (1000), A124364 (10000), A124362 (100000), A124368 (1000000).

Sequences for initial term k: A124263 (k=3), A124267 (5), A124291 (7), A124290 (11), A124298 (13), A124299 (17), A124336 (23), A124310 (29), A124335 (31), A124337 (37), A124338 (41).

Programs

Mathematica

NestList[NextPrime[10 #, -1]&, 2, 20] (* Vincenzo Librandi, Jun 28 2014 *)

PARI

step(k)=precprime(10*k)
my(t=1/5); vector(10,n,t=step(t)) \\ Charles R Greathouse IV, Sep 14 2015