OFFSET
0,2
LINKS
Daniel Suteu, Table of n, a(n) for n = 0..750
FORMULA
a(n) = (2n - 1)^2 * (n + 1).
Prod_{k >= 1}(A033430(k) / a(k)) = Pi.
MATHEMATICA
Table[4n^3 - 3n + 1, {n, 0, 39}] (* Alonso del Arte, Dec 25 2016 *)
PROG
(PARI) a(n) = (2*n-1)^2 * (n+1).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Daniel Suteu, Dec 25 2016
STATUS
approved