释义 |
Plouffe's ConstantN.B. A detailed on-line essay by S. Finchwas the starting point for this entry.
Define the function
| (1) |
Let
| (2) |
then
| (3) |
For
| (4) |
and
| (5) |
Letting
| (6) |
then
| (7) |
Plouffe asked if the above processes could be ``inverted.'' He considered
giving
| (9) |
and
| (10) |
giving
| (11) |
and
| (12) |
giving
| (13) |
The latter is known as Plouffe's constant (Plouffe 1997). The positions of the 1s in the Binary expansion ofthis constant are 3, 6, 8, 9, 10, 13, 21, 23, ... (Sloane's A004715).
Borwein and Girgensohn (1995) extended Plouffe's to arbitrary Real , showingthat if
| (14) |
then
| (15) |
Borwein and Girgensohn (1995) also give much more general recurrences and formulas. References
Borwein, J. M. and Girgensohn, R. ``Addition Theorems and Binary Expansions.'' Canad. J. Math. 47, 262-273, 1995.Finch, S. ``Favorite Mathematical Constants.'' http://www.mathsoft.com/asolve/constant/plff/plff.html Plouffe, S.. ``The Computation of Certain Numbers Using a Ruler and Compass.'' Dec. 12, 1997.http://www.research.att.com/~njas/sequences/JIS/compass.html. Sloane, N. J. A. Sequence A004715in ``The On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html. |