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A091708
Number of primes less than 10^n having at least one digit 7.
10
1, 9, 68, 549, 4819, 43506, 397756, 3681943, 34344296, 322199867, 3036544958, 28722439343, 272501681533, 2591959274190
OFFSET
1,2
EXAMPLE
a(1) = 1 because of the 4 primes less than 10^1, 1 has at least one digit 7.
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], 7] != {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)
Table[Count[Prime[Range[PrimePi[10^n]]], _?(DigitCount[#, 10, 7]>0&)], {n, 12}] (* Harvey P. Dale, Mar 03 2013 *)
CROSSREFS
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