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Search: id:A059840
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| A059840 |
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F(n)*F(n-1) if n odd otherwise F(n)*F(n-1)-1, where F = Fibonacci numbers A000045. |
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+0
8
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| 0, 0, 2, 5, 15, 39, 104, 272, 714, 1869, 4895, 12815, 33552, 87840, 229970, 602069, 1576239, 4126647, 10803704, 28284464, 74049690, 193864605, 507544127, 1328767775, 3478759200, 9107509824, 23843770274, 62423800997, 163427632719
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,500
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FORMULA
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G.f.: g(x)=(2x^2+x^3-x^4)/((1-x^2)(1-2x-2x^2+x^3)) - Mario Catalani (mario.catalani(AT)unito.it), Jan 28 2003
a(n) = Sum [ F(k)*F(k+2), {k,1,n-2} ]. - Alexander Adamchuk (alex(AT)kolmogorov.com), May 17 2007
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PROGRAM
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(PARI) { b=0; f=1; for (n=1, 500, a=f*b; if (frac(n/2)==0, a--); write("b059840.txt", n, " ", a); a=f + b; b=f; f=a; ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jun 29 2009]
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CROSSREFS
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Cf. A000045, A059248, A064831, A001654, A119996.
Sequence in context: A148339 A148340 A148341 this_sequence A148342 A148343 A148344
Adjacent sequences: A059837 A059838 A059839 this_sequence A059841 A059842 A059843
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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), Feb 26 2001
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