OFFSET
0,2
LINKS
F. Luca and I. E. Shparlinski, On the squarefree parts of floor(e*n!), Glasgow Math. J., 49 (2007), 391-403.
FORMULA
a(n) = core(A000522(n)).
MAPLE
A000522 := proc(n)
add( n!/k!, k=0..n) ;
end proc:
A222637 := proc(n)
end proc: # R. J. Mathar, Jan 16 2014
MATHEMATICA
core[n_] := Times @@ Power @@@ ({#[[1]], Mod[#[[2]], 2]}& /@ FactorInteger[n]);
a[n_] := If[n == 0, 1, core[Floor[E*n!]]];
Table[a[n], {n, 0, 22}] (* Jean-François Alcover, Apr 04 2024 *)
PROG
(PARI) a(n) = core(n! * polcoeff(exp(x + x*O(x^n)) / (1 - x), n))
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Feb 27 2013
STATUS
approved