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A331046
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Numbers k such that floor(k/10^m) is a prime number for some m >= 0.
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1
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2, 3, 5, 7, 11, 13, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 43, 47, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 67, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 83, 89, 97, 101, 103, 107, 109, 110, 111, 112, 113
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OFFSET
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1,1
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COMMENTS
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In other words, these are the numbers with a prime prefix.
For any m > 0:
- let f(m) be the proportion of positive numbers <= 10^m belonging to this sequence,
- also f(m) <= f(m+1) <= 1,
- so {f(m)} has a limit, say F, as m tends to infinity,
- what is the value of F?
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LINKS
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EXAMPLE
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The number 2 is prime, so every number in A217394 belongs to this sequence.
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PROG
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(PARI) is(n, base=10) = while (n, if (isprime(n), return (1), n\=base)); return (0)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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