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Search: id:A121813
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| A121813 |
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quartic third term expansion recursion. |
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+0
1
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| 0, 1, 1, 1, 1, 4, 13, 121, 8401, 17724001, 19980403610080, 3017939125082738100693961, 1069257489122187637992525695378883464262898201
(list; graph; listen)
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OFFSET
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1,6
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FORMULA
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a(n) = a[n] = a[ -4 + n] a[ -3 + n] a[ -2 + n] + a[ -4 + n] a[ -3 + n] a[ -1 + n] + a[ -4 + n] a[ -2 + n] a[ -1 + n] + a[ -3 + n] a[ -2 + n] a[ -1 + n]
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EXAMPLE
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ExpandAll[ (x + a[n - 1])*(x + a[n - 2])*(x + a[n - 3])*(x + a[n - 4])]
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MATHEMATICA
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a[0] = 0; a[1] = 1; a[2] = 1; a[3] = 1; a[n_] : a[n] = a[ -4 + n] a[ -3 + n] a[ -2 + n] + a[ -4 + n] a[ -3 + n] a[ -1 + n] + a[ -4 + n] a[ -2 + n] a[ -1 + n] + a[ -3 + n] a[ -2 + n] a[ -1 + n] b = Table[a[n], {n, 0, 15}]
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CROSSREFS
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Adjacent sequences: A121810 A121811 A121812 this_sequence A121814 A121815 A121816
Sequence in context: A058014 A045886 A015460 this_sequence A006104 A067634 A042537
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KEYWORD
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nonn,uned
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AUTHOR
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Roger Bagula (rlbagulatftn(AT)yahoo.com), Aug 30 2006
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