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A228421

Count of the first 10^n primes which do not contain the digit 9.

1, 8, 69, 620, 5010, 45732, 418142, 3785060, 32579606, 296601070, 2683254222, 24354108057, 212324183352

OFFSET

0,2

LINKS

FORMULA

a(n) <= 9^n. - Charles R Greathouse IV, May 21 2014

EXAMPLE

a(1) = 8 since there are 8 primes in the first 10 (through 29) that do not contain a 9. Namely: 2, 3, 5, 7, 11, 13, 17, 23.

MATHEMATICA

Table[Length[Select[Range[10^n], DigitCount[Prime[#], 10, 9] == 0 &]], {n, 0, 5}] (* Robert Price, Mar 23 2020 *)

PROG

(Python)

def a(n):

count = 0

for k in range(1, 10**n+1):

if '9' not in str(prime(k)):

count += 1

return count

n = 0

while n < 10:

print(a(n), end=', ')

n += 1

# Derek Orr, Jul 27 2014

CROSSREFS

KEYWORD

more,nonn,base,hard

AUTHOR

Robert Price, Nov 09 2013

EXTENSIONS

a(12) from Lucas A. Brown, Mar 19 2024

STATUS

approved

URL: https://oeis.org/A228421