A120873 Fractal sequence of the Wythoff difference array (A080164).
1, 1, 2, 3, 1, 4, 2, 5, 6, 3, 7, 8, 1, 9, 4, 10, 11, 2, 12, 5, 13, 14, 6, 15, 16, 3, 17, 7, 18, 19, 8, 20, 21, 1, 22, 9, 23, 24, 4, 25, 10, 26, 27, 11, 28, 29, 2, 30, 12, 31, 32, 5, 33, 13, 34, 35, 14, 36, 37, 6, 38, 15, 39, 40, 16, 41, 42, 3, 43, 17, 44, 45, 7, 46, 18, 47, 48, 19, 49
Offset: 1
Keywords
Examples
The fractal sequence f(n) of a dispersion D={d(g,h,)} is defined as follows. For each positive integer n there is a unique (g,h) such that n=d(g,h) and f(n)=g. So f(7)=2 because the row of the WDA in which 7 occurs is row 2.
References
- Clark Kimberling, The Wythoff difference array, in Applications of Fibonacci Numbers, vol.10, Proceedings of the Eleventh International Conference on Fibonacci Numbers and Their Applications, William Webb, editor, Congressus Numerantium, Winnipeg, Manitoba 194 (2009) 153-158.
Links
- Michel Marcus, Table of n, a(n) for n = 1..10000
- N. J. A. Sloane, Classic Sequences.
Programs
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PARI
lowerw(n) = (n+sqrtint(5*n^2))\2 ; \\ A000201 upperw(n) = (sqrtint(n^2*5)+n*3)\2; \\ A001950 compoundw(n) = (sqrtint(n^2*5)+n*3)\2 - 1; \\ A003622 a(n) = my(x=lowerw(n), y=upperw(n), u); while (1, my(k=1, ok=1); while(ok, my(xx = lowerw(k), yy = compoundw(k)); if ((x == xx) && (y == yy), return(k)); if (xx > x, ok = 0); k++;); u = x; x = y - u; y = u;); \\ Michel Marcus, Sep 17 2022
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