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A158510
Generalized Fibonacci numbers Fib(n + 0.5) rounded to an integer.
1
1, 1, 1, 2, 4, 6, 10, 17, 27, 43, 70, 113, 183, 296, 480, 776, 1255, 2031, 3287, 5318, 8605, 13924, 22529, 36452, 58981, 95433, 154414, 249848, 404262, 654109, 1058371, 1712481, 2770852, 4483332, 7254184, 11737517, 18991701, 30729218, 49720919
OFFSET
0,4
COMMENTS
Generalized Fib(x) = (phi^x - cos(x*Pi) / phi^x) / sqrt(5) where phi = (1 + sqrt(5))/2.
Apparently, these are also the rounded geometric means of consecutive Fibonacci numbers. - Vladimir Reshetnikov, Mar 10 2021
LINKS
EXAMPLE
a(7) = 17 because Fib(7.5) = 16.51666... which rounds to 17.
MATHEMATICA
f[n_] := Round[(GoldenRatio^n - Cos[n*Pi]/GoldenRatio^n)/Sqrt[5]]; Array[f, 39, .5] (* Robert G. Wilson v, Jun 19 2014 *)
PROG
(PARI) { default(realprecision, 130); s5 = sqrt(5); phi = (1 + s5)/2.0; for (n=0, 500, x=n+0.5; f = round((phi^x - cos(x*Pi) / phi^x) / s5); write("b158510.txt", n, " ", f)) }
CROSSREFS
Cf. A001622.
Sequence in context: A091611 A107742 A228779 * A004695 A014216 A192683
KEYWORD
nonn
AUTHOR
Harry J. Smith, Mar 20 2009
STATUS
approved