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A228419
Count of the first 10^n primes which do not contain the digit 7.
0
1, 8, 67, 539, 5034, 45549, 416913, 3570781, 32517377, 294828478, 2681147149, 23720397369, 212156228217
OFFSET
0,2
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 7. Namely: 2, 3, 5, 11, 13, 19, 23, 29.
MATHEMATICA
Table[Length[Select[Range[10^n], DigitCount[Prime[#], 10, 7] == 0 &]], {n, 0, 5}] (* Robert Price, Mar 23 2020 *)
KEYWORD
more,nonn,base,hard
AUTHOR
Robert Price, Nov 09 2013
EXTENSIONS
a(12) from Lucas A. Brown, Mar 19 2024
STATUS
approved