A293319 Greatest integer k such that k/2^n < tau^2, where tau = (1+sqrt(5))/2 = golden ratio.
2, 5, 10, 20, 41, 83, 167, 335, 670, 1340, 2680, 5361, 10723, 21446, 42893, 85787, 171575, 343150, 686301, 1372603, 2745207, 5490415, 10980830, 21961660, 43923321, 87846643, 175693286, 351386573, 702773147, 1405546295, 2811092590, 5622185180, 11244370361
Offset: 0
Links
- Clark Kimberling, Table of n, a(n) for n = 0..1000
Programs
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Magma
[Floor((2^n*(3+Sqrt(5)))/2): n in [0..33]]; // Vincenzo Librandi, Oct 08 2017
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Mathematica
z = 120; r = 1+GoldenRatio; Table[Floor[r*2^n], {n, 0, z}]; (* A293319 *) Table[Ceiling[r*2^n], {n, 0, z}]; (* A293320 *) Table[Round[r*2^n], {n, 0, z}]; (* A293321 *)
Formula
a(n) = floor((r*2^n)), where r = (3+sqrt(5))/2.
a(n) = A293320(n) - 1.