login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A307376 a(n) = 1/n! * Sum_{k=0..n} (2*n+k)!/((n-k)!*k!*2^k). 1
1, 5, 81, 2330, 97405, 5360607, 366432990, 29948982492, 2849278444155, 309333396512855, 37741150862494651, 5112458462852223210, 761358344010536141506, 123636426598733578925150, 21742842987398075489784900, 4116720379411455407932693320, 834934865669512891440715729125 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..313

FORMULA

a(n) = (-1)^n * A144505(2*n+1, n).

a(n) ~ 3^(3*n + 1/2) * n^(n - 1/2) / (sqrt(Pi) * 2^(n + 1/2) * exp(n - 2/3)). - Vaclav Kotesovec, Apr 06 2019

MATHEMATICA

Table[Sum[(2*n + k)!/((n - k)!*k!*2^k)/n!, {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Apr 06 2019 *)

PROG

(PARI) {a(n) = sum(k=0, n, (2*n+k)!/((n-k)!*k!*2^k))/n!}

CROSSREFS

Cf. A144505.

Sequence in context: A135918 A115032 A278883 * A009733 A009756 A188419

Adjacent sequences:  A307373 A307374 A307375 * A307377 A307378 A307379

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Apr 06 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 18 01:05 EST 2020. Contains 330995 sequences. (Running on oeis4.)