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Search: id:A043327
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| A043327 |
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a(0)=1; a(1)=1; a(n)= a(n-1) + floor( sqrt(a(n-1)*a(n-2))+ sqrt(a(n-3)*a(n-4))+ ... ). |
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+0
2
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| 1, 1, 2, 3, 6, 11, 22, 43, 85, 166, 327, 641, 1259, 2471, 4853, 9528, 18710, 36737, 72137, 141643, 278125, 546112, 1072322, 2105559, 4134379, 8118070, 15940263, 31299549, 61458328, 120676683, 236955071, 465273846, 913589879, 1793882179
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Nonlinear recurrence similar to that for Narayana numbers.
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MATHEMATICA
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a[ 0 ]=0; a[ 1 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+ Floor[ Plus@@Map[ Sqrt[ Times@@# ]&, Partition[ Reverse[ Array[ a, n, 0 ] ], 2 ] ] ]
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CROSSREFS
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Cf. A002083, A043328.
Sequence in context: A043328 A002083 A124973 this_sequence A005578 A058050 A026418
Adjacent sequences: A043324 A043325 A043326 this_sequence A043328 A043329 A043330
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KEYWORD
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nonn,easy
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AUTHOR
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Olivier Gerard (olivier.gerard(AT)gmail.com), Jul 18 2001.
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