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Search: id:A053287
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| 1, 2, 6, 8, 30, 36, 126, 128, 432, 600, 1936, 1728, 8190, 10584, 27000, 32768, 131070, 139968, 524286, 480000, 1778112, 2640704, 8210080, 6635520, 32400000, 44717400, 113467392, 132765696, 533826432, 534600000, 2147483646
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Number of elements of multiplicative order 2^n-1 in GF(2^n).
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..100
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FORMULA
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a(n)=A000010[A000225(n)]
a[n]=A000010[2^n-1] or also a[n]=A062401(2^(n-1))=phi[sigma[2^(n-1)]. - Labos E. (labos(AT)ana.sote.hu), Jul 19 2004
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MAPLE
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with(numtheory):with(combinat):a:=n->phi(stirling2(n, 2)): seq(a(n), n=2..32); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 05 2007
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MATHEMATICA
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Table[EulerPhi[DivisorSigma[1, 2^w]], {w, 0, 25}] Table[EulerPhi[2^w-1], {w, 1, 25}]
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CROSSREFS
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Cf. A000010, A000225, A051953, A057764.
Adjacent sequences: A053284 A053285 A053286 this_sequence A053288 A053289 A053290
Sequence in context: A056188 A020696 A132269 this_sequence A086323 A075999 A096999
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KEYWORD
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nonn,easy,nice
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Mar 03 2000
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