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Search: id:A070550
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| A070550 |
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a(n) = a(n-1) + a(n-3) + a(n-4). |
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+0
4
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| 1, 2, 2, 3, 6, 10, 15, 24, 40, 65, 104, 168, 273, 442, 714, 1155, 1870, 3026, 4895, 7920, 12816, 20737, 33552, 54288, 87841, 142130, 229970, 372099, 602070, 974170, 1576239, 2550408, 4126648, 6677057, 10803704, 17480760, 28284465, 45765226
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Shares some properties with Fibonacci sequence.
The sum of any two alternating terms (terms separated by one other term) produces a Fibonacci number (e.g. 2+6=8, 3+10=13, 24+65=89, etc.) The product of any two consecutive or alternating Fibonacci terms produces a term from this series. (e.g. 5x8=40, 13x5=65, 21x8=168, etc.)
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FORMULA
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a(n) = F[floor(n/2)+1]*F[ceiling(n/2)+2], with F(n) = A000045(n). - R. Stephan, Apr 14 2004
G.f.: (1+x)/(1-x-x^3-x^4)= (1+x)/((1+x^2)*(1-x-x^2)).
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CROSSREFS
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a(2n) = F(n+1)F(n+2) = A001654(n+1), a(2n+1) = F(n+1)F(n+3) = A059929(n+1).
Adjacent sequences: A070547 A070548 A070549 this_sequence A070551 A070552 A070553
Sequence in context: A077074 A054200 A137216 this_sequence A102762 A049853 A064319
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KEYWORD
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easy,nonn
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AUTHOR
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Sreyas Srinivasan (sreyas_srinivasan(AT)hotmail.com), May 02 2002
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EXTENSIONS
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More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), May 03 2002
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