OFFSET
0,1
COMMENTS
LINKS
Robert Grizzard and Joseph Gunther, Slicing the stars: counting algebraic numbers, integers, and units by degree and height, arXiv:1609.08720 [math.NT] 2016.
MATHEMATICA
a[d_] := (e = Floor[(d-1)/2]; 2^(d+1) (d+1)^e Product[(2k)^(d-2k)/(2k+1)^( d+1-2k), {k, 1, e}]) // Floor;
PROG
(PARI) a(n) = floor(2^(n+1)*(n+1)^((n-1)\2)*prod(k=1, (n-1)\2, (2*k)^(n-2*k)/(2*k+1)^(n+1-2*k))); \\ Jinyuan Wang, Mar 05 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Sondow, May 26 2017
EXTENSIONS
More terms from Jinyuan Wang, Mar 05 2020
STATUS
approved