A283773 Numbers k such that U(k) = 1 mod 3, where U = A001950 = upper Wythoff sequence.
3, 4, 5, 11, 12, 13, 19, 20, 27, 28, 35, 36, 42, 43, 44, 50, 51, 52, 58, 59, 60, 66, 67, 68, 74, 75, 82, 83, 90, 91, 97, 98, 99, 105, 106, 107, 113, 114, 115, 121, 122, 123, 129, 130, 137, 138, 144, 145, 146, 152, 153, 154, 160, 161, 162, 168, 169, 170, 176
Offset: 1
Links
- Clark Kimberling, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
r = GoldenRatio^2; z = 350; t = Table[Floor[n*r], {n, 1, z}]; u = Mod[t, 3]; Flatten[Position[u, 0]] (* A283772 *) Flatten[Position[u, 1]] (* A283773 *) Flatten[Position[u, 2]] (* A283774 *)
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PARI
r = (3 + sqrt(5))/2; for(n=1, 351, if(floor(n*r)%3==1, print1(n,", "))) \\ Indranil Ghosh, Mar 19 2017
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Python
import math from sympy import sqrt r = (3 + sqrt(5))/2 [n for n in range(1, 351) if int(math.floor(n*r))%3==1] # Indranil Ghosh, Mar 19 2017
Formula
a(n+1) - a(n) is in {1,6,7} for every n.
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