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Search: id:A057772
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| 1, 0, 1, 0, 2, 1, 4, 4, 12, 15, 34, 55, 110, 190, 370, 664, 1272, 2350, 4466, 8372, 15926, 30105, 57390, 109202, 208738, 398985, 764906, 1467370, 2820770, 5427543, 10459456, 20176561, 38969684, 75339232, 145804978, 282429242, 547573768
(list; graph; listen)
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OFFSET
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1,5
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REFERENCES
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P. J. Cameron, Some counting problems related to permutation groups, Discrete Math., 225 (2000), 77-92.
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MAPLE
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with(numtheory): ietr:= proc(p) local a, c; c:= proc(n) option remember; local j; n*p(n)-add(c(j)*p(n-j), j=1..n-1) end; a:=proc(n) option remember; local d; `if`(n=0, 1, add (mobius (n/d)*c(d), d=divisors(n))/n) end end: a := ietr(n-> add (phi(d) *2^(n/d)/2/n, d=select (m-> modp(m, 2)=1, divisors(n)))): seq (a(n), n=1..37); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 08 2008]
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CROSSREFS
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Sequence in context: A095293 A034409 A048049 this_sequence A145861 A129874 A021983
Adjacent sequences: A057769 A057770 A057771 this_sequence A057773 A057774 A057775
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Nov 02 2000
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EXTENSIONS
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Better definition and more terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 13 2008
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