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Search: id:A069749
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| A069749 |
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Number of primes less than 10^n containing only the digits 2 and 3 (A020458). |
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+0
1
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| 2, 3, 5, 7, 11, 18, 31, 44, 83, 135, 239, 436, 818, 1436, 2773, 4695, 9244, 17022, 32948, 58158, 116040, 214188
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(22) / A006880(22) = 214188 / 201467286689315906290 =~ 10^-15. But out of the 2^22 candidates for primes, ~5% are.
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MATHEMATICA
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s = 0; Do[k = 0; While[k < 2^n, k++; If[p = FromDigits[ PadLeft[ IntegerDigits[k, 2], n] + 2]; PrimeQ[p], s++ ]]; Print[s], {n, 1, 22}]
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CROSSREFS
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Cf. A006880, A020458 & A036937.
Sequence in context: A038887 A067904 A018146 this_sequence A081889 A078139 A120628
Adjacent sequences: A069746 A069747 A069748 this_sequence A069750 A069751 A069752
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KEYWORD
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base,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 22 2002
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