A216044 - OEIS

A216044

Numbers k such that Sum_{j=1..k-1} (4j)!/16^j is an integer.

1, 3, 13, 15, 61, 106, 253, 27545, 62785, 218107, 1004593

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OFFSET

1,2

COMMENTS

Next term > 1200000.

LINKS

MATHEMATICA

seq={}; sum=0; fak=1; k=0; While[k<10000, sum+=fak; If[Denominator[sum]==1, AppendTo[seq, k+1]]; k++; fak*=k*(4*k-1)*(4*k-2)*(4*k-3)/4; ]; seq

CROSSREFS

KEYWORD

nonn,more

AUTHOR

STATUS

approved