A037064 a(n)-th prime is the smallest prime containing exactly n 6's.

1, 18, 121, 859, 15226, 54070, 1071206, 3933314, 34614430, 309084622, 2792083255, 61496476037, 1214237371612, 5255429125063, 105341326636887, 458846460486827, 15441107727480784, 16660543186177748, 832868428561305574, 1494006786965549890, 14206605445888164436, 135418222271099812357

Offset: 0

Author

Patrick De Geest, Jan 04 1999

Keywords

• nonn
• base
• hard

Links

• Andrew R. Booker, The Nth Prime Page.
• Kim Walisch, primecount, Fast prime counting function library.

Crossrefs

Cf. A000720, A037065, A034388.

Cf. A037052, A037054, A037056, A037058, A037060, A037062, A037066, A037068, A037070.

Programs

Mathematica

(* see A037065 for f *) PrimePi[ Table[ f[n, 6], {n, 1, 12}]]

Formula

a(n) = A000720(A037065(n)). - Amiram Eldar, Jul 20 2025

Extensions

One more terms from Hans Havermann, Jun 16 2001

a(0)=1 prepended by Sean A. Irvine, Dec 06 2020

a(13)-a(21) calculated using Kim Walisch's primecount and added by Amiram Eldar, Jul 20 2025