|
|
A216045
|
|
Numbers k such that Sum_{j=1..k-1} (4j)!/5^j is an integer.
|
|
5
|
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Next term is > 1500000.
|
|
LINKS
|
|
|
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
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|