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A091705
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Number of primes less than 10^n having at least one digit 4.
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5
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0, 3, 32, 326, 3231, 31953, 310456, 3000349, 28922364, 278508004, 2680391313, 25793058269
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| a(2) = 3 because of the 25 primes less than 10^2, 3 have at least one digit 4.
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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], 4] != {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (from Robert G. Wilson v Feb 02 2004)
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CROSSREFS
| a(n) + A091638(n) = A006880(n).
Cf. A091744, A091745, A091746, A091747, A091706, A091707, A091708, A091709, A091710.
Sequence in context: A037673 A037799 A091706 * A137215 A123336 A058479
Adjacent sequences: A091702 A091703 A091704 * A091706 A091707 A091708
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KEYWORD
| nonn,base
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AUTHOR
| Enoch Haga (Enokh(AT)comcast.net), Jan 30 2004
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 02 2004
3 more terms from Ryan Propper (rpropper(AT)stanford.edu), Aug 21 2005
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