A046856 a(n) = (2^n)!/4^n, with a(1)=1, a(2)=2.

1, 2, 630, 81729648000, 256963707943060088053923840000000, 30978254928194376001814792318154658399137088909801072314160618743948902400000000000000

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

The next term has 212 digits. - Harvey P. Dale, May 31 2021

Links

• C. S. Lorens, Invertible Boolean functions, IEEE Trans. Electron. Computers, EC-13 (1964), 529-541.
• C. S. Lorens, Invertible Boolean functions, IEEE Trans. Electron. Computers, EC-13 (1964), 529-541. [Annotated scan of page 530 only]

Programs

Maple

a:= n-> ceil((2^n)!/4^n):
seq(a(n), n=1..6);  # Alois P. Heinz, May 31 2021

Mathematica

Join[{1,2},Table[(2^n)!/4^n,{n,3,6}]] (* Harvey P. Dale, May 31 2021 *)