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A158564
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Generalized Fibonacci numbers round(abs(Fib(n*I))), I=sqrt(-1).
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1
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0, 5, 120, 2771, 64120, 1483771, 34335480, 794546793, 18386363119, 425473177569, 9845744025606, 227837336237557, 5272313768144476, 122004992372201577, 2823280028149695952, 65332655347676516331, 1511842896283885073147
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OFFSET
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0,2
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COMMENTS
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Generalized Fib(x) = (phi^x - cos(x*Pi) / phi^x) / sqrt(5) where phi = (1 + sqrt(5))/2.
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LINKS
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EXAMPLE
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a(2) = 120 because Fib(2*I) = -68.179... + 98.623... * I, whose absolute value is 119.895..., and rounded gives 120.
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PROG
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(PARI) { default(realprecision, 150); s5 = sqrt(5); phi = (1 + s5)/2.0; for (n=0, 100, x=n*I; f = round(abs((phi^x - cos(x*Pi) / phi^x) / s5)); write("b158564.txt", n, " ", f)) }
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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