A091636 Number of primes less than 10^n which do not contain the digit 2.

3, 22, 139, 877, 6235, 46105, 352155, 2747284, 21831323, 175881412, 1432781905, 11778245565, 97558533214, 813253056497

Offset

1,1

Comments

Number of primes less than 10^n after removing any primes with at least one digit 2.

Links

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

Formula

a(n) = A006880(n) - A091646(n).

Example

a(2) = 22 because of the 25 primes less than 10^2, 3 have at least one digit 2. 25-3 = 22.

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], 2] == {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)

Prog

(Python)
from sympy import primerange
def a(n): return sum('2' not in str(p) for p in primerange(2, 10**n))
print([a(n) for n in range(1, 7)]) # Michael S. Branicky, Mar 22 2021

Crossrefs

Cf. A091634, A091635, A091637, A091638, A091639, A091640, A091641, A091642, A091643, A091646.

Cf. A006880, A091646.

Sequence in context: A100511 A033506 A091639 * A321003 A339227 A215051

Adjacent sequences: A091633 A091634 A091635 * A091637 A091638 A091639

Keyword

more,nonn,base

Author

Enoch Haga, Jan 30 2004

Extensions

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

a(9)-a(12) from Donovan Johnson, Feb 14 2008

a(13) from Robert Price, Nov 08 2013

a(14) from Giovanni Resta, Mar 20 2017

Status

approved