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Search: id:A097926
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| A097926 |
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Number of (n,4) Freiman-Wyner sequences. |
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+0
3
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| 18, 36, 70, 134, 258, 498, 960, 1850, 3566, 6874, 13250, 25540, 49230, 94894, 182914, 352578, 679616, 1310002, 2525110, 4867306, 9382034, 18084452, 34858902, 67192694, 129518082, 249654130, 481223808, 927588714, 1787984734, 3446451386
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OFFSET
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5,1
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COMMENT
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"The values for n <= 4 are straightforward."
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REFERENCES
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I. F. Blake, The enumeration of certain run length sequences, Information and Control, 55 (1982), 222-237.
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FORMULA
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a(n)=2a(n-1)-a(n-k-1), k=4, n>=2k+2. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 31 2006
G.f.: -2*(5*x^3+8*x^2+9*x+9)*x^5/(x^4+x^3+x^2+x-1) = -10*x^4-6*x^3-2*x^2-2+(-2*x^3-2+2*x)/(x^4+x^3+x^2+x-1) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 18 2007
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MAPLE
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A097926 := proc(nmax) local a, n, k; k := 4 ; a := [18, 36, 70, 134, 258] ; while nops(a) < nmax do n := nops(a)+k+1 ; a := [op(a), 2*op(n-1-k, a)-op(n-2*k-1, a) ] ; od ; end: nmax := 30 ; a := A097926(nmax) ; for i from 1 to nmax do printf("%d, ", op(i, a)) ; od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 31 2006
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CROSSREFS
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Cf. A006355, A097925.
Sequence in context: A131766 A154575 A011799 this_sequence A087967 A070224 A083211
Adjacent sequences: A097923 A097924 A097925 this_sequence A097927 A097928 A097929
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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), Sep 05 2004
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 31 2006
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