A124339 -id:A124339 - cp's OEIS frontend

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

Artur Jasinski, Dec 16 2006

nonn

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

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).

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

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

A126031 a(n) is the largest prime < 3*a(n-1) for n > 1, with a(1) = 2.

Original entry on oeis.org

2, 5, 13, 37, 109, 317, 947, 2837, 8501, 25471, 76403, 229199, 687593, 2062759, 6188263, 18564769, 55694299, 167082893, 501248653, 1503745949, 4511237741, 13533713213, 40601139629, 121803418861, 365410256543, 1096230769619, 3288692308841, 9866076926507, 29598230779511

Offset: 1

Artur Jasinski, Dec 16 2006

nonn

Artur Jasinski, Table of n, a(n) for n = 1..40

Similar sequences for a(n) = largest prime < m*a(n-1): A006992 (m=2), this sequence (3), A124190 (4), A126033 (5), A126034 (6), A126035 (7), A126036 (8), A126037 (9), A124262 (10), A126039 (11), A126040 (12), A124339 (100), A124361 (1000), A124364 (10000), A124362 (100000), A124368 (1000000).

NestList[NextPrime[3#,-1]&,2,30] (* Harvey P. Dale, Feb 03 2012 *)

A124358 Largest prime < 100*a(n-1), a(1) = 5.

Original entry on oeis.org

5, 499, 49891, 4989079, 498907883, 49890788291, 4989078829037, 498907882903681, 49890788290368043, 4989078829036804253, 498907882903680425207, 49890788290368042520691, 4989078829036804252069087, 498907882903680425206908691, 49890788290368042520690869043

Offset: 1

Artur Jasinski, Dec 16 2006

nonn

James C. McMahon, Table of n, a(n) for n = 1..100

Cf. A124267, A124339.

a[1]=5;a[n_]:=NextPrime[100a[n-1],-1];Table[a[n],{n,15}] (* James C. McMahon, Dec 15 2024 *)

a(13)-(15) from James C. McMahon, Dec 15 2024

A124357 Largest prime < 100*a(n-1), a(1)=3.

Original entry on oeis.org

3, 293, 29297, 2929699, 292969877, 29296987651, 2929698765083, 292969876508291, 29296987650829069, 2929698765082906837, 292969876508290683679, 29296987650829068367867, 2929698765082906836786649, 292969876508290683678664841, 29296987650829068367866484043

Offset: 1

Artur Jasinski, Dec 16 2006

nonn

Cf. A124262, A124263, A124339.

NestList[NextPrime[100#,-1]&,3,15] (* Harvey P. Dale, Oct 05 2011 *)

More terms from Harvey P. Dale, Oct 05 2011

cp's OEIS Frontend

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

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A126031 a(n) is the largest prime < 3*a(n-1) for n > 1, with a(1) = 2.

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A124358 Largest prime < 100*a(n-1), a(1) = 5.

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A124357 Largest prime < 100*a(n-1), a(1)=3.

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