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A098020 Let f[n] = fractional part of n*Pi and let g[x] = -1 for the range 0<=x<=1/3, g[x] = 0 for the range 1/3<x<=2/3, g[x] = 11 for range 2/3<x<1. Sequence gives all positive integers n such that f[n+2]-2*f[n+1]+f[n]]-g[f[n+1]] = 0. 0
2, 3, 9, 10, 16, 17, 23, 24, 30, 31, 37, 38, 39, 44, 45, 46, 51, 52, 53, 58, 59, 60, 65, 66, 67, 72, 73, 74, 80, 81, 87, 88, 94, 95, 101, 102, 108, 109, 115, 116, 122, 123, 129, 130, 136, 137, 143, 144, 150, 151, 152, 157, 158, 159, 164, 165, 166, 171, 172, 173, 178 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Irrational rotation of Pi as an implicit sequence with an uneven Cantor cartoon.

LINKS

Table of n, a(n) for n=1..61.

MATHEMATICA

f[n_]=Mod[Pi*n, 1]; digits=200; (* uneven Cantor type function*); g[x_]:=-1/ ; 0<=x<=1/3; g[x_]:=0/; 1/3<x<=2/3; g[x_]:=11/; 1/3<x<=1; a=Delete[Union[Table[If [N[f[n+2]-2*f[n+1]+f[n]]-g[f[n+1]]==0, n, 0], {n, 1, digits}]], 1]

CROSSREFS

Sequence in context: A191568 A279549 A030743 * A047358 A280731 A003140

Adjacent sequences:  A098017 A098018 A098019 * A098021 A098022 A098023

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Sep 09 2004

EXTENSIONS

Edited by N. J. A. Sloane, Jun 24 2007

STATUS

approved

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Last modified September 24 17:09 EDT 2020. Contains 337321 sequences. (Running on oeis4.)