A231794 Count of the first 10^n primes containing at least one 7's digit.

2, 33, 461, 4966, 54451, 583087, 6429219, 67482623, 705171522, 7318852851, 76279602631

Offset: 1

Author

Robert Price, Nov 13 2013

Keywords

• more
• nonn
• base

Examples

			a(2)=33 because there are 33 primes not greater than 541 (the 100th prime) that contain a 7's digit.  Namely: 7, 17, 37, 47, 67, 71, 73, 79, 97, 107, 127, 137, 157, 167, 173, 179, 197, 227, 257, 271, 277, 307, 317, 337, 347, 367, 373, 379, 397, 457, 467, 479, 487.
		

Crossrefs

Cf. A231726-A231790, A231792-A231796, A091634-A091643, A231412, A228413-A228421.

Programs

Mathematica

cnt = 0; Table[Do[p = Prime[k]; If[MemberQ[IntegerDigits[p], 7], cnt++], {k, 10^(n - 1) + 1, 10^n}]; cnt, {n, 5}] (* T. D. Noe, Nov 13 2013 *)

Formula

a(n) ~ 10^n. - Charles R Greathouse IV, May 21 2014