OFFSET
1,3
COMMENTS
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
MAPLE
A000793:=
[1, 2, 3, 4, 6, 6, 12, 15, 20, 30, 30, 60, 60, 84, 105, 140,
210, 210, 420, 420, 420, 420, 840, 840, 1260, 1260, 1540,
2310, 2520, 4620, 4620, 5460, 5460, 9240, 9240, 13860,
13860, 16380, 16380, 27720, 30030, 32760, 60060, 60060,
60060, 60060, 120120]:
a:=proc(n)
global A000793;
local k;
for k from 1 do
if A000793[n]^k >= n! then return k; fi;
od;
end;
MATHEMATICA
b[n_, i_] := b[n, i] = Module[{p}, p = If[i < 1, 1, Prime[i]]; If[n == 0 || i < 1, 1, Max[b[n, i - 1], Table[p^j b[n - p^j, i - 1], {j, 1, Log[p, n] // Floor}]]]];
a[n_] := Module[{m}, If[n == 1, 1, m = b[n, If[n < 8, 3, PrimePi[Ceiling[ 1.328 Sqrt[n Log[n] // Floor]]]]]; Log[m, n!] // Ceiling]];
CROSSREFS
KEYWORD
nonn
AUTHOR
W. Edwin Clark, May 27 2013
STATUS
approved