A216045 Numbers k such that Sum_{j=1..k-1} (4j)!/5^j is an integer.

1, 6, 30, 145, 151, 592, 732, 3895, 87806, 292432

Offset

1,2

Comments

Next term is > 1500000.

Links

Table of n, a(n) for n=1..10.

Mathematica

seq={}; sum=0; fak=1; k=0; While[k<10000, sum+=fak; If[Denominator[sum]==1, AppendTo[seq, k+1]]; k++; fak*=4*k*(4*k-1)*(4*k-2)*(4*k-3)/5; ]; seq

Crossrefs

Cf. A215972, A216042, A216043, A216044.

Sequence in context: A135160 A276022 A046945 * A307494 A316593 A089817

Adjacent sequences: A216042 A216043 A216044 * A216046 A216047 A216048

Keyword

nonn,more

Author

Vaclav Kotesovec, Aug 30 2012

Status

approved