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A139669
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Number of isomorphism classes of finite groups of order 11*2^n.
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1
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OFFSET
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0,2
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COMMENTS
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This appears to be the smallest possible number of groups of order q*2^n for an odd number q.
Apparently, a(n) is also the number of isomorphism classes of finite groups of order 19*2^n and, more generally, of order p*2^n for primes p such that p is congruent to 3 modulo 4 and p+1 is not a power of 2.
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REFERENCES
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J. H. Conway et al., The Symmetries of Things, Peters, 2008, p. 206.
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LINKS
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FORMULA
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EXAMPLE
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a(2) is the number of groups of order 11*2^2=44, which is 4 and also the number of groups of order 19*2^2=76, 23*2^2=92, etc.
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MAPLE
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A139669 := n -> GroupTheory[NumGroups](11*2^n);
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CROSSREFS
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KEYWORD
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hard,more,nonn
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AUTHOR
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Anthony D. Elmendorf (aelmendo(AT)calumet.purdue.edu), Jun 12 2008
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EXTENSIONS
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STATUS
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approved
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