A091706 Number of primes less than 10^n having at least one digit 5.

1, 3, 32, 324, 3282, 31949, 309669, 2995706, 28891689, 278270868, 2678674624, 25780340194, 248131741834, 2388797604792

Offset

1,2

Links

Table of n, a(n) for n=1..14.

Example

a(1) = 1 because of the 4 primes less than 10^1, 1 has at least one digit 5.

Mathematica

NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; c = 0; p = 1; Do[ While[ p = NextPrim[p]; p < 10^n, If[ Position[ IntegerDigits[p], 5] != {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)
Table[Count[Prime[Range[PrimePi[10^n]]], _?(DigitCount[#, 10, 5]>0&)], {n, 8}] (* Harvey P. Dale, Dec 29 2012 *)

Crossrefs

a(n) + A091639(n) = A006880(n).

Cf. A091644, A091645, A091646, A091647, A091705, A091707, A091708, A091709, A091710.

Sequence in context: A037792 A037673 A037799 * A091705 A137215 A300366

Adjacent sequences: A091703 A091704 A091705 * A091707 A091708 A091709

Keyword

nonn,base

Author

Enoch Haga, Jan 30 2004

Extensions

Edited and extended by Robert G. Wilson v, Feb 02 2004

3 more terms from Ryan Propper, Aug 21 2005

a(13) from Robert Price, Nov 11 2013

a(14) from Giovanni Resta, Jul 21 2015

Status

approved