A216043 Numbers k such that Sum_{j=1..k-1} (2j)!/3^j is an integer.

1, 4, 12, 105, 112, 322, 8807, 8831

Offset: 1

Author

Vaclav Kotesovec, Aug 30 2012

Keywords

• nonn
• more

Comments

Next term > 2000000.

Crossrefs

Cf. A215972, A216042, A216044, A216045

Programs

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