OFFSET
1,2
COMMENTS
Prime p divides a(2p-1), p>3. Prime p divides a(3p-1), p>2. Prime p divides a(p-1), p>3. p^2 divides a(p^2-1) for prime p>3. p^3 divides a(p^3-1) for prime p>3. p^4 divides a(p^4-1) for prime p>3. p^5 divides a(p^5-1) for p>3.
FORMULA
a(n) = numerator( Sum_{i=1..n} i^3/(n-i+1) ).
MATHEMATICA
Numerator[Table[Sum[i^3/(n-i+1), {i, 1, n}], {n, 1, 50}]]
CROSSREFS
KEYWORD
frac,nonn
AUTHOR
Alexander Adamchuk, Jun 25 2006
STATUS
approved