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 A053159 Numbers n such that n+cototient(n) is a power of 2. 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS See especially A053579 and also A053576, A053577. LINKS Donovan Johnson, Table of n, a(n) for n = 1..100 FORMULA a(n)+A051953(n) = 2*a(n)-A000010(n) = 2^w for some w. EXAMPLE Mersenne primes are a proper subset of this sequence: A(M)=2M-M+1=M+1=2^p PROG (PARI) print(1); for(n=3, 10^9, if(omega(2*n-eulerphi(n))==1, print(n))) /* Donovan Johnson, Apr 04 2013 */ CROSSREFS Cf. A000043, A000668, A001348. Sequence in context: A366044 A031328 A255180 * A345891 A279912 A305477 Adjacent sequences: A053156 A053157 A053158 * A053160 A053161 A053162 KEYWORD nonn AUTHOR Labos Elemer, Feb 29 2000 EXTENSIONS More terms from Reiner Martin, Dec 24 2001 STATUS approved

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Last modified September 16 15:55 EDT 2024. Contains 375976 sequences. (Running on oeis4.)