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Search: id:A053579
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| A053579 |
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Composite numbers whose cototient (A051953) is a power of 2. |
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+0
5
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| 4, 6, 8, 12, 14, 16, 24, 28, 32, 48, 56, 62, 64, 96, 112, 124, 128, 192, 224, 248, 254, 256, 384, 448, 496, 508, 512, 768, 896, 992, 1016, 1024, 1536, 1792, 1984, 2032, 2048, 3072, 3584, 3968, 4064, 4096, 6144, 7168, 7936, 8128, 8192, 12288, 14336
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OFFSET
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1,1
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EXAMPLE
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If n=3*2^s, cototient[n]=3*2^s-2*2^(s-1)=2^(s+1); if n=7*2^s, cototient[n]=(7-6)*2^(s-1)=2^(s+2). If cototient[x]=32768, then arguments are 3*16384,7*8192,31*2048,127*512,8191*8 and 65536. If n=(2^w)*q, where q is a Mersenne prime, then Phi(n)=(q-1)*2^(w-1) and the cototient(n)= is 2^(w-1)*(2q-q+1)=2^(w-1)*(q+1)=2^(w-1+s).
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CROSSREFS
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Cf. A051953.
Sequence in context: A090697 A107303 A028876 this_sequence A074121 A055670 A141096
Adjacent sequences: A053576 A053577 A053578 this_sequence A053580 A053581 A053582
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jan 18 2000
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