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Search: id:A037289
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| A037289 |
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Number of commutative rings with n elements. |
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+0
4
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| 1, 2, 2, 9, 2, 4, 2, 34, 9, 4, 2, 18, 2, 4, 4, 162, 2, 18, 2, 18, 4, 4, 2, 68, 9, 4, 36, 18, 2, 8, 2
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This sequence may be multiplicative. - Mitch Harris, Apr 19 2005
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LINKS
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C. Noebauer, Home page
C. Noebauer, The Numbers of Small Rings
C. Noebauer, Thesis on the enumeration of near-rings
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CROSSREFS
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Cf. A027623, A037291.
Sequence in context: A125313 A082838 A074961 this_sequence A037290 A155936 A167594
Adjacent sequences: A037286 A037287 A037288 this_sequence A037290 A037291 A037292
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KEYWORD
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nonn,nice,hard
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AUTHOR
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Christian G. Bower (bowerc(AT)usa.net), Jun 15 1998.
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EXTENSIONS
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a(16) from Christof Noebauer (christof.noebauer(AT)algebra.uni-linz.ac.at), Sep 29, 2000, who reports that the sequence continues a(32) = ? (> 876), a(33) = 4, 4, 4, 81, 2, 4, 4, 68, 2, 8, 2, 18, 18, 4, 2, 324, 9, 18, 4, 18, 2, 72, 4, 68, 4, 4, 2, 36, 2, 4, 18 = a(63), a(64) = ? (> 12696)
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