A037068 a(n)-th prime is the smallest prime containing exactly n 8's.

1, 23, 152, 1107, 8611, 70478, 1793210, 5156463, 45470645, 2074530409, 11397691034, 33578243459, 1603686087003, 2859644709998, 26622184513952, 518238694402971, 2339285051888769, 69641948074252447, 208626752630607267, 8383527978057824838, 119921750787289924042, 375732914981870085595

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, A037069, A034388.

Cf. A037052, A037054, A037056, A037058, A037060, A037062, A037064, A037066, A037070.

Programs

Mathematica

(* see A037069 for f *) PrimePi[ Table[ f[n, 8], {n, 1, 13}]]

Formula

a(n) = A000720(A037069(n)). - Amiram Eldar, Jul 21 2025

Extensions

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

a(12) corrected and a(13)-a(21) calculated using Kim Walisch's primecount and added by Amiram Eldar, Jul 21 2025