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Search: id:A073950
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| A073950 |
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Number of strings over Z_3 of length n with trace 1 and subtrace 0. |
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+0
6
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| 1, 2, 3, 9, 30, 81, 225, 702, 2187, 6561, 19602, 59049, 177633, 532170, 1594323, 4782969, 14351094, 43046721, 129127041, 387400806
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Same as number of strings over Z_3 of length n with trace 2 and subtrace 0. Same as number of strings over GF(3) of length n with trace 1 and subtrace 0. Same as number of strings over GF(3) of length n with trace 2 and subtrace 0.
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LINKS
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F. Ruskey, Strings over Z_3 of given Trace and Subtrace
F. Ruskey, Strings over GF(3) of given Trace and Subtrace
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FORMULA
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a(n; t, s) = a(n-1; t, s) + a(n-1; t+2, s+2t+1) + a(n-1; t+1, s+t+1) where t is the trace and s is the subtrace.
G.f.: q*(q-1)*(3*q^3-3*q^2+3*q-1)/[(1-3q)(1+3q^2)(1-3q+3q^2)]. - Lawrence Sze, Oct 24 2004
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CROSSREFS
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Cf. A073947, A073948, A073949, A073951, A073952.
Adjacent sequences: A073947 A073948 A073949 this_sequence A073951 A073952 A073953
Sequence in context: A099079 A006797 A139006 this_sequence A064020 A095412 A074428
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KEYWORD
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easy,nonn
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AUTHOR
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Frank Ruskey, Nate Kube (fruskey(AT)cs.uvic.ca), Aug 15 2002
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