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Search: id:A138366
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| A138366 |
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Count of post-period decimal digits up to which the rounded n-th convergent to exp(1) agrees with the exact value. |
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+0
8
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| 0, 1, 0, 1, 2, 3, 4, 5, 5, 6, 7, 7, 8, 9, 10, 12, 12, 13, 14, 16, 15, 16, 19, 18, 20, 22, 22, 24, 25, 25, 26, 27, 28, 30, 32, 32, 32, 35, 36, 36, 39, 39, 41, 43, 43, 44, 46, 46, 48, 50, 50, 52, 52, 54, 56, 57, 58, 59, 61, 61, 63, 65, 64, 67, 69, 69, 71, 72, 73, 74, 77, 77, 79, 80, 81, 83
(list; graph; listen)
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OFFSET
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1,5
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COMMENT
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This is a measure of the quality of the n-th convergent to E = A001113 if the
convergent and the exact value are compared rounded to an increasing number of digits.
The sequence of rounded values of exp(1) is
3, 2.7, 2.72, 2.718, 2.7183, 2.71828, 2.718282, 2.7182818 etc, and the n-th convergent
(provided by A007676 and A007677) is to be represented by its equivalent sequence.
a(n) represents the maximum number of post-period digits of the two sequences
if compared at the same level of rounding. Counting only post-period digits (which is
one less than the full number of decimal digits) is just a convention taken from A084407.
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EXAMPLE
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For n=6, the 6th convergent is 106/39 = 2.7179487.., with a sequence of rounded
representations 3, 2.7, 2.72, 2.718, 2.7179, 2.71795, 2.717949, etc.
Rounded to 1, 2, or 3 post-period decimal digits, this is the same as the rounded version
of the exact E, but disagrees if both are rounded to 4 decimal digits, where 2.7183 <> 2.7179.
So a(n=6)= 3 (digits), the maximum rounding level of agreement.
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CROSSREFS
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Cf. A138335, A138336, A138337, A138338, A138339, A138343, A138367, A138369, A138370.
Sequence in context: A125051 A064067 A020892 this_sequence A065515 A070545 A091863
Adjacent sequences: A138363 A138364 A138365 this_sequence A138367 A138368 A138369
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KEYWORD
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nonn,base
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Mar 17 2008
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EXTENSIONS
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Definition and values replaced as defined via continued fractions - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 01 2009
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