A358361 - OEIS

A358361

Decimal expansion of the constant Sum_{j>=0} j!!/(2*j)!, where j!! indicates the double factorial of j.

1, 5, 8, 7, 7, 0, 2, 6, 4, 7, 7, 2, 7, 6, 6, 0, 5, 0, 7, 9, 7, 1, 8, 0, 1, 2, 6, 6, 2, 8, 5, 5, 5, 3, 7, 3, 2, 2, 3, 5, 4, 8, 6, 2, 3, 2, 4, 6, 7, 7, 2, 1, 2, 5, 2, 7, 5, 1, 6, 3, 2, 0, 4, 7, 3, 5, 6, 6, 5, 1, 0, 4, 0, 4, 6, 7, 1, 8, 6, 9, 5, 4, 9, 5, 5, 2, 2

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Sum_{j>=0} j!!/(2j)! converges since Sum_{j>=0} j!!/j! converges by A143280 (and it is trivial to note that (2*j)! >= j! for any positive integer j).

LINKS

Table of n, a(n) for n=1..87.

Eric Weisstein's World of Mathematics, Double Factorial.

FORMULA

Equals Sum_{j>=0} A006882(j)/A010050(j).

Equals Sum_{j>=0} 1/(A264152(j)*j!).

EXAMPLE