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A216043
Numbers k such that Sum_{j=1..k-1} (2j)!/3^j is an integer.
5
1, 4, 12, 105, 112, 322, 8807, 8831
OFFSET
1,2
COMMENTS
Next term > 2000000.
MATHEMATICA
seq={}; sum=0; fak=1; k=0; While[k<10000, sum+=fak; If[Denominator[sum]==1, AppendTo[seq, k+1]]; k++; fak*=2*k*(2k-1)/3; ]; seq
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vaclav Kotesovec, Aug 30 2012
STATUS
approved