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A053159
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Numbers n such that n+cototient(n) is a power of 2.
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2
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1, 3, 7, 10, 20, 31, 40, 80, 127, 160, 320, 322, 640, 644, 1280, 1288, 2560, 2576, 5120, 5152, 8191, 10240, 10304, 20480, 20608, 40960, 41216, 81920, 82432, 131071, 163840, 164864, 327680, 329728, 333634, 524287, 655360, 659456, 667268, 1310720, 1318912
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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Mersenne primes are a proper subset of this sequence: A(M)=2M-M+1=M+1=2^p
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PROG
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(PARI) print(1); for(n=3, 10^9, if(omega(2*n-eulerphi(n))==1, print(n))) /* Donovan Johnson, Apr 04 2013 */
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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