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URL: https://oeis.org/A293246

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A293246
a(n) is the smallest k > 1 such that A000166(k) is divisible by n!.
0
2, 2, 3, 7, 25, 121, 241, 1681, 13441, 40321, 403201, 2016001, 3225601, 41932801, 609638401
OFFSET
0,1
COMMENTS
a(n) is the smallest k > 1 such that round(k!/e) is divisible by n!.
Terms are 0! + 1, 1! + 1, 2! + 1, 3! + 1, 4! + 1, 5! + 1, 6!/3 + 1, 7!/3 + 1, ...
EXAMPLE
a(3) = 7 because the smallest nonzero subfactorial number that is divisible by 3! is A000166(7) = 1854.
MAPLE
f:= proc(n) local k, t, p;
p:= n!;
t:= 0;
for k from 2 do
t:= k*t + (-1)^k mod p;
if t = 0 then return k fi
od:
end proc:
seq(f(n), n=0..13); # Robert Israel, Oct 03 2017
CROSSREFS
Sequence in context: A083701 A076996 A139148 * A038507 A185387 A077001
KEYWORD
nonn,more
AUTHOR
Altug Alkan, Oct 03 2017
EXTENSIONS
a(8)-a(14) from Robert Israel, Oct 03 2017
STATUS
approved