login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A129326
a(n) = (2*n+1)*(n-1)!.
9
3, 5, 14, 54, 264, 1560, 10800, 85680, 766080, 7620480, 83462400, 997920000, 12933043200, 180583603200, 2702527027200, 43153254144000, 732297646080000, 13160434839552000, 249692574523392000, 4987449116762112000, 104614786351595520000, 2299092397726924800000
OFFSET
1,1
COMMENTS
a(n) = A052649(n-1), n > 1 (i.e., A052649 with a(0) omitted).
LINKS
FORMULA
a(n) = A052649(n-1), n > 1. - R. J. Mathar, Jun 14 2008
a(n) = (n+1)!*h(n+1) - n*(n+1)*(n-1)!*h(n-1), where h(n) = Sum_{k=1..n} 1/k. - Gary Detlefs, Jul 19 2011
E.g.f.: 2*x/(1-x) - log(1-x). - G. C. Greubel, Nov 02 2018
Sum_{n>=1} 1/a(n) = e/2 - sqrt(Pi)*erfi(1)/4. - Amiram Eldar, Oct 07 2020
MATHEMATICA
Table[(2n+1)(n-1)!, {n, 30}] (* Harvey P. Dale, Mar 23 2012 *)
PROG
(Magma) [(2*n+1)*Factorial(n-1): n in [1..25]]; // Vincenzo Librandi, Aug 07 2011
(PARI) vector(30, n, (2*n+1)*(n-1)!) \\ G. C. Greubel, Nov 02 2018
CROSSREFS
Cf. A052649.
Sequence in context: A078718 A081393 A338368 * A167553 A370612 A118562
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, May 26 2007
EXTENSIONS
More terms from N. J. A. Sloane, Nov 08 2007
STATUS
approved