OFFSET
1,1
COMMENTS
a(113) has 997 digits and a(114) has 1007 digits. - Harvey P. Dale, Nov 24 2024
LINKS
Harry J. Smith, Table of n, a(n) for n=1..100
FORMULA
a(n) = 4^n * Gamma(1 + n + n^2)/Gamma(1 - n + n^2). - G. C. Greubel, May 06 2022
EXAMPLE
a(3) = 14*16*18*20*22*24 = 42577920.
MATHEMATICA
Table[4^n*Gamma[1+n+n^2]/Gamma[1-n+n^2], {n, 30}] (* G. C. Greubel, May 05 2022 *)
Module[{nn=20, ev, l}, ev=2*Range[nn(nn+1)]; l=2*Range[nn]; Times@@@TakeList[ev, l]] (* Harvey P. Dale, Nov 24 2024 *)
PROG
(PARI) { for(n=1, 100, write("b062030.txt", n, " ", 2^(2*n)*(n^2+n)!/(n^2-n)!) ) } \\ Harry J. Smith, Jul 30 2009
(SageMath) [4^n*gamma(1+n+n^2)/gamma(1-n+n^2) for n in (1..30)] # G. C. Greubel, May 05 2022
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Amarnath Murthy, Jun 02 2001
EXTENSIONS
More terms from Jason Earls, Jun 10 2001
Typo in a(4) corrected by N. J. A. Sloane, Aug 31 2009 using the b-file.
STATUS
approved