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A053288
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Cototient of 2^n-1.
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0
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0, 1, 1, 7, 1, 27, 1, 127, 79, 423, 111, 2367, 1, 5799, 5767, 32767, 1, 122175, 1, 568575, 319039, 1553599, 178527, 10141695, 1154431, 22391463, 20750335, 135669759, 3044479, 539141823, 1, 2147483647, 1626398143, 5726972583, 1835106367, 42598088703, 616318399, 91627367079, 84561979327, 625809227775
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| Number of elements in GF(2^n) that do not have maximal order. a(n)=1 if n is the exponent of a Mersenne prime, the single element which is not a generator for these is the unit. [Joerg Arndt, Jul 05 2011]
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FORMULA
| a(n) = A051593(A000225(n))
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PROG
| (PARI) a(n)={local(m=2^n-1); return(m-eulerphi(m)); }
vector(66, n, a(n)) /* show terms */ /* Joerg Arndt, Jul 05 2011 */
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CROSSREFS
| Cf. A000010, A000225, A051953.
Sequence in context: A147347 A183109 A082172 * A050301 A146996 A083994
Adjacent sequences: A053285 A053286 A053287 * A053289 A053290 A053291
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Mar 03 2000
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