|
| |
|
|
A132189
|
|
Number of non-constant 3-term geometric progressions with no term exceeding n.
|
|
2
| |
|
|
0, 0, 0, 2, 2, 2, 2, 4, 8, 8, 8, 10, 10, 10, 10, 16, 16, 20, 20, 22, 22, 22, 22, 24, 32, 32, 36, 38, 38, 38, 38, 44, 44, 44, 44, 54, 54, 54, 54, 56, 56, 56, 56, 58, 62, 62, 62, 68, 80, 88, 88, 90, 90, 94, 94, 96, 96, 96, 96, 98, 98, 98, 102, 116, 116, 116, 116, 118, 118, 118
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,4
|
|
|
COMMENTS
| In racetrack language, this is the number of trifectas in geometric progression in an n-horse race.
It appears that geometric progression like (k,0,0) are excluded. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 24 2007
|
|
|
REFERENCES
| Gerry Myerson, Trifectas in Geometric Progression, Australian Mathematical Society Gazette, 2008, to appear.
|
|
|
MATHEMATICA
| a = {}; For[n = 1, n < 80, n++, c = 0; For[j = 1, j < n + 1, j++, For[h = 1, h < n + 1, h++, If[Not[h == j], If[IntegerQ[j*(h/j)^2], If[j*(h/j)^2 < n + 1, c++ ]]]]]; AppendTo[a, c]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 24 2007
|
|
|
CROSSREFS
| Sequence in context: A103260 A060824 A064849 * A162799 A034585 A171869
Adjacent sequences: A132186 A132187 A132188 * A132190 A132191 A132192
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Gerry Myerson (gerry(AT)ics.mq.edu.au), Nov 21 2007
|
|
|
EXTENSIONS
| More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 24 2007
|
| |
|
|
