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Search: id:A071118
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| A071118 |
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Size of the automorphism group of the group Z X Z_n. |
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+0
1
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| 2, 4, 12, 16, 40, 24, 84, 64, 108, 80, 220, 96, 312, 168, 240, 256, 544, 216, 684, 320, 504, 440, 1012, 384, 1000, 624, 972, 672, 1624, 480, 1860, 1024, 1320, 1088, 1680, 864, 2664, 1368, 1872, 1280, 3280, 1008, 3612, 1760, 2160, 2024, 4324, 1536
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OFFSET
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1,1
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COMMENT
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This automorphism group is isomorphic to Z_2 X G where G is the group described in A002618.
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FORMULA
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a(n) = 2 * A002618(n) = 2 * n * Phi(n).
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MATHEMATICA
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Table[ 2n*EulerPhi[n], {n, 1, 45}]
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PROGRAM
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(PARI) for(n=1, 100, print1(2*n*eulerphi(n), ", "))
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CROSSREFS
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Cf. A002618, A000010.
Sequence in context: A067268 A082458 A114064 this_sequence A132314 A053636 A054440
Adjacent sequences: A071115 A071116 A071117 this_sequence A071119 A071120 A071121
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KEYWORD
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nonn
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AUTHOR
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Sharon Sela (sharonsela(AT)hotmail.com), May 28 2002
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EXTENSIONS
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Edited by Robert G. Wilson v (rgwv(AT)rgwv.com) and Benoit Cloitre (benoit7848c(AT)orange.fr), May 28 2002
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