A090977 Least k such that k*prime(k) > 10^n.

1, 3, 7, 17, 48, 134, 382, 1115, 3287, 9786, 29296, 88181, 266694, 809599, 2465574, 7528976, 23045352, 70684657, 217196605, 668461874, 2060257099, 6358076827, 19644205359, 60757729194, 188099056251, 582846849914, 1807483210259, 5609430824151, 17420628067997

Offset

0,2

Comments

Does lim_{n->oo} a(n+1)/a(n) exist? If so, is the limit Pi? - Ryan Propper, Sep 15 2005

Links

Robert G. Wilson v, Table of n, a(n) for n = 0..36 (terms 1..36 from Chai Wah Wu).

Example

a(3) = 17 as 17*prime(17) = 17*59 = 1003 > 10^3.

Maple

for n from 0 to 11 do b:=proc(k) if k*ithprime(k)>10^n then k else fi end: a[n]:=[seq(b(k), k=1..100000)][1]: od: seq(a[n], n=0..11); # Emeric Deutsch, Aug 04 2005

Mathematica

n = 0; For[k = 1, k > 0, k++, If[k*Prime[k] > 10^n, Print[k]; n++ ]] (* Ryan Propper, Sep 15 2005 and modified by Robert G. Wilson v, Feb 25 2019 to reflect the offset of 0 *)

Crossrefs

Sequence in context: A071985 A181419 A371866 * A324789 A014144 A247183

Adjacent sequences: A090974 A090975 A090976 * A090978 A090979 A090980

Keyword

nonn,base

Author

Amarnath Murthy, Jan 04 2004

Extensions

More terms from Emeric Deutsch, Aug 04 2005

More terms from Ryan Propper, Sep 15 2005

a(20)-a(28) from Chai Wah Wu, Apr 29 2018

a(0)=1 prepended by Robert G. Wilson v, Feb 25 2019

Status

approved