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Search: id:A138807
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| A138807 |
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a(n) = floor: Pi*a(n-1) + a(n-2). |
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+0
1
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| 0, 1, 3, 10, 37, 128, 439, 1508, 5179, 17779, 61033, 209522, 719266, 2469165, 8476377, 29098491, 99891986, 342918422, 1177201983, 4041207525, 13873029857, 47624616207, 163490174266, 561244146614
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OFFSET
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0,3
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COMMENT
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a(n)/a(n-1) tends to 3.4328922159... = exp ArcSinh(Pi/2).
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FORMULA
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a(n) = floor: Pi*a(n-1) * a(n-2); a(0) = 0, a(1) = 1; n>1. a(n) = floor of terms (1,2) and (2,2) of the 2 X 2 matrix [0,1; 1,Pi]^n
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EXAMPLE
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a(4) = 37 since [0,1; 1,Pi]^4 = [10.869..., 37.289...; 37.289..., 128.017...].
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CROSSREFS
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Sequence in context: A010373 A104603 A080625 this_sequence A149043 A151315 A164048
Adjacent sequences: A138804 A138805 A138806 this_sequence A138808 A138809 A138810
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KEYWORD
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nonn
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Mar 30 2008
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