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Date: 19-3-2020
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The Pierce expansion, or alternated Egyptian product, of a real number is the unique increasing sequence of positive integers such that
(1) |
A number has a finite Pierce expansion iff is rational.
Special cases are summarized in the following table.
OEIS | Pierce expansion | |
A091831 | 1, 3, 8, 33, 35, 39201, 39203, 60245508192801, ... | |
Catalan's constant | A132201 | 1, 11, 13, 59, 582, 12285, 127893, 654577, ... |
A118239 | 1, 2, 12, 30, 56, 90, 132, 182, 240, ... | |
A020725 | 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ... | |
Euler-Mascheroni constant | A006284 | 1, 2, 6, 13, 21, 24, 225, 615, 17450, ... |
natural logarithm of 2 | A091846 | 1, 3, 12, 21, 51, 57, 73, 85, 96, ... |
A118242 | 1, 2, 4, 17, 19, 5777, 5779, 192900153617, ... | |
A006283 | 3, 22, 118, 383, 571, 635, 70529, ... | |
1, 2, 3, 8, 9, 24, 37, 85, ... | ||
A068377 | 1, 6, 20, 42, 72, 110, 156, 210, 272, ... |
If is of the form
(2) |
then there is a closed-form for the Pierce expansion given by
(3) |
where
(4) |
|||
(5) |
and (Shallit 1984). This recurrence has explicit solution
(6) |
not noted by Shallit (1984).
, corresponding to , has the particularly beautiful form
(7) |
|||
(8) |
where is a Fibonacci number.
The following table gives coefficients and for some small integer .
OEIS | OEIS | ||||
3 | A001999 | 3, 18, 5778, 192900153618, ... | A006276 | 2, 4, 17, 19, 5777, 5779, ... | |
4 | 4, 52, 140452, 2770663499604052, ... | 3, 5, 51, 53, 140451, 140453, ... | |||
5 | 5, 110, 1330670, 2356194280407770990, ... | 4, 6, 109, 111, 1330669, 1330671, ... | |||
6 | A112845 | 6, 198, 7761798, 467613464999866416198, ... | A006275 | 5, 5, 7, 197, 199, 7761797, ... |
REFERENCES:
Erdős, P. and Shallit, J. O. "New Bounds on the Length of Finite Pierce and Engel Series." Sem. Theor. Nombres Bordeaux 3, 43-53, 1991.
Keselj, V. "Length of Finite Pierce Series: Theoretical Analysis and Numerical Computations." Sep. 10, 1996. https://www.cs.uwaterloo.ca/research/tr/1996/21/cs-96-21.pdf.
Mays, M. E. "Iterating the Division Algorithm." Fib. Quart. 25, 204-213, 1987.
Pierce, T. A. "On an Algorithm and Its Use in Approximating Roots of Polynomials." Amer. Math. Monthly 36, 523-525, 1929.
Salzer, H. E. "The Approximation of Numbers as Sums of Reciprocals." Amer. Math. Monthly 54, 135-142, 1947.
Shallit, J. O. "Some Predictable Pierce Expansions." Fib. Quart. 22, 332-335, 1984.
Shallit, J. O. "Metric Theory of Pierce Expansions." Fib. Quart. 24, 22-40, 1986.
Sloane, N. J. A. Sequences A001999/M3055, A006275/M1342, A006283/M3092, A006284/M1593, A006276/M1298, A020725, A091831, A091846, A112845, A118242, and A132201 in "The On-Line Encyclopedia of Integer Sequences."
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