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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS 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 a(n) + A091641(n) = A006880(n). Cf. A091644, A091645, A091646, A091647, A090705, A090706, A091707, A091709, A091710. Sequence in context: A194650 A048742 A121633 * A327560 A024119 A348590 Adjacent sequences:  A091705 A091706 A091707 * A091709 A091710 A091711 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

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Last modified May 20 17:47 EDT 2022. Contains 353876 sequences. (Running on oeis4.)