OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..314
S.-S. Chern, A simple intrinsic proof of the Gauss-Bonnet formula for closed Riemannian manifolds, Ann. of Math. (2) 45 (1944) 747-752.
FORMULA
a(n) = floor((4*Pi)^n * n!).
EXAMPLE
a(5) = 37603698 = floor(2^(2 * 5) * Pi^5 * 120) = floor (37603698.9).
MATHEMATICA
Table[Floor[4^n*(Pi^n)*n!], {n, 0, 50}] (* G. C. Greubel, Jul 28 2017 *)
PROG
(PARI) A163585(n)={ floor((4*Pi)^n*n!) }
{ realprecision=120 ; for(n=1, 20, print1(A163585(n), ", ") ; ); } \\ R. J. Mathar, Aug 07 2009
(Python)
from mpmath import mp, pi, fac
mp.dps = 120
def a(n): return int(floor((4*pi)**n*fac(n)))
print([a(n) for n in range(21)]) # Indranil Ghosh, Jul 28 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jul 31 2009
EXTENSIONS
More terms from R. J. Mathar, Aug 07 2009
New name using formula, Joerg Arndt, Jul 30 2017
STATUS
approved