|
|
A214869
|
|
Decimal expansion of Sum_{n >= 1} n!/(2*n)!.
|
|
7
|
|
|
5, 9, 2, 2, 9, 6, 5, 3, 6, 4, 6, 9, 3, 2, 6, 5, 7, 5, 6, 6, 0, 4, 1, 5, 0, 5, 4, 5, 3, 9, 0, 6, 2, 6, 8, 7, 2, 8, 4, 6, 1, 6, 6, 1, 2, 2, 1, 6, 9, 8, 7, 1, 0, 3, 7, 7, 5, 6, 8, 5, 8, 3, 6, 5, 3, 2, 0, 3, 6, 7, 9, 6, 1, 6, 6, 5, 0, 7, 5, 5, 7, 0, 2, 7, 2, 4, 4, 3, 5, 1, 5, 7, 5, 0, 7, 6, 1, 0, 4, 2, 5, 5, 3, 5, 3
(list;
constant;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
COMMENTS
|
Equivalent to: 1/2 e^(1/4) Pi^(1/2) erf(1/2) where erf(1/2) is error function.
|
|
LINKS
|
Eric Weisstein's World of Mathematics, Erf
|
|
EXAMPLE
|
0.5922965364693265756604150545390626872846166122169...
|
|
MAPLE
|
|
|
MATHEMATICA
|
NSum[n!/(2 n)!, {n, 1, Infinity}, WorkingPrecision -> 105]
|
|
PROG
|
(PARI) /* needs GP version >= 2.6 */
N=200;
default(realprecision, N+10);
s=suminf(n=1, n!/(2*n)!);
digits( floor( 10^N*s ), 10 )
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|