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Search: id:A081093
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| A081093 |
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Smallest prime having in binary representation prime(n) number of 1's. |
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+0
2
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OFFSET
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1,1
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COMMENT
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a(n) = Min{p: A000120(p)=A000040(n), p prime}.
If 2^(Prime[n]) - 1 is a prime number, then a(n) = 2^(Prime[n]) - 1, where Prime[n] denotes the n-th prime number. This means that every Mersenne prime arises in this sequence. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jan 22 2006
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EXAMPLE
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a(5)=3583=A081092(266)=A000040(502) having eleven 1's: '110111111111', and A000120(p)<11=prime(5) for primes p<3583.
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CROSSREFS
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Cf. A000040, A000120, A081092.
Cf. A000668 - the Mersenne prime numbers.
Sequence in context: A084924 A001348 A006515 this_sequence A093535 A057612 A136005
Adjacent sequences: A081090 A081091 A081092 this_sequence A081094 A081095 A081096
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Mar 05 2003
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EXTENSIONS
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a(9) from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jan 22 2006
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