

A195326


Numerators of fractions leading to e  1/e (A174548).


1



0, 2, 2, 7, 7, 47, 47, 5923, 5923, 426457, 426457, 15636757, 15636757, 7318002277, 7318002277, 1536780478171, 1536780478171, 603180793741, 603180793741, 142957467201379447, 142957467201379447
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OFFSET

0,2


COMMENTS

The sequence of approximations of exp(1) obtained by truncating the Taylor series of exp(x) after n terms is A061354(n)/A061355(n) = 1, 2, 5/2, 8/3, 65/24, ...
A Taylor series of exp(1) is 1, 0, 1/2, 1/3, 3/8, ... and (apart from the first 2 terms) given by A000255(n)/A001048(n). Subtracting both sequences term by term we obtain a series for exp(1)  exp(1) = 0, 2, 2, 7/3, 7/3, 47/20, 47/20, 5923/2520, 5923/2520, 426457/181440, 426457/181440, ... which defines the numerators here.
Each second of the denominators (that is 3, 2520, 19958400, ...) is found in A085990 (where each third term, that is 60, 19958400, ...) is to be omitted.
This numerator sequence here is basically obtained by doubling entries of A051397, A009628, A087208, or A186763, caused by the standard associations between cosh(x), sinh(x) and exp(x).


LINKS



EXAMPLE

a(0) = 1  1;
a(1) = 2  0;
a(2) = 5/2  1/2.


MAPLE

taylExp1 := proc(n)
add(1/j!, j=0..n) ;
end proc:
if n <=1 then
1;
else
n*procname(n1)+(n1)*procname(n2) ;
end if;
end proc:
n!+(n1)! ;
end proc:
if n = 0 then
0;
elif n =1 then
2;
else
end if;
numer(%);
end proc:


CROSSREFS



KEYWORD

nonn,frac


AUTHOR



EXTENSIONS

Material meant to be placed in other sequences removed by R. J. Mathar, Oct 14 2011


STATUS

approved



