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Search: id:A043328
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| A043328 |
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a(0)=1; a(1)=1; a(n)= a(n-1) + floor(sqrt(a(n-1)*a(n-2))) + floor(sqrt(a(n-3)*a(n-4))) + .... |
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+0
2
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| 1, 1, 2, 3, 6, 11, 22, 42, 83, 162, 318, 623, 1224, 2402, 4717, 9261, 18185, 35706, 70111, 137665, 270313, 530772, 1042200, 2046413, 4018242, 7890029, 15492492, 30420327, 59731927, 117286804, 230298862, 452204027, 887926594, 1743490958
(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[ 2 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+ Plus@@Map[ Floor[ Sqrt[ Times@@# ] ]&, Partition[ Reverse[ Array[ a, n, 0 ] ], 2 ] ]
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CROSSREFS
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Cf. A002083, A043327.
Sequence in context: A018613 A036589 A123341 this_sequence A002083 A124973 A043327
Adjacent sequences: A043325 A043326 A043327 this_sequence A043329 A043330 A043331
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KEYWORD
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nonn,easy
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AUTHOR
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Olivier Gerard (ogerard(AT)ext.jussieu.fr), Jul 18 2001.
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