A037060 a(n)-th prime is the smallest prime containing exactly n 4's.

1, 13, 86, 603, 4620, 37299, 1533327, 22568442, 23574105, 210014510, 1893613727, 17241353173, 493582559244, 13474975578701, 71056054875827, 1180956491651370, 10728352138939963, 103710009988272649, 960912626678471376, 1005142876338508545, 50686811139876408310, 288867303325879381560

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, A037061, A034388.

Cf. A037052, A037054, A037056, A037058, A037062, A037064, A037066, A037068, A037070.

Programs

Mathematica

(* see A037061 for f *) PrimePi[ Table[ f[n, 4], {n, 1, 12}]]

Formula

a(n) = A000720(A037061(n)). - Amiram Eldar, Jul 20 2025

Extensions

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