OFFSET
1,2
FORMULA
a(n) = denominator(n*(n + 1)*(2*n + 1)/6/(n!)^2).
EXAMPLE
MATHEMATICA
Table[Denominator[n*(n + 1)*(2*n + 1)/(6*(n!)^2)], {n, 1, 18}] (* Amiram Eldar, May 09 2020 *)
PROG
(PARI) a(n) = denominator(sum(k=1, n, k^2)/prod(k=1, n, k^2)); \\ Michel Marcus, May 09 2020
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Petros Hadjicostas, May 09 2020
STATUS
approved