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A216043 Numbers n such that Sum( (2k)!/3^k, k=1..n-1 ) is integral. 5
1, 4, 12, 105, 112, 322, 8807, 8831 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Next term > 2000000

LINKS

Table of n, a(n) for n=1..8.

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

Cf. A215972, A216042, A216044, A216045

Sequence in context: A012278 A070040 A079822 * A245647 A080448 A155174

Adjacent sequences:  A216040 A216041 A216042 * A216044 A216045 A216046

KEYWORD

nonn,more

AUTHOR

Vaclav Kotesovec, Aug 30 2012

STATUS

approved

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Last modified October 15 12:31 EDT 2019. Contains 328026 sequences. (Running on oeis4.)