A072489 a(1) = 1, a(n) = a(n-1) times smallest divisor of n >= n^(1/2).

1, 2, 6, 12, 60, 180, 1260, 5040, 15120, 75600, 831600, 3326400, 43243200, 302702400, 1513512000, 6054048000, 102918816000, 617512896000, 11732745024000, 58663725120000

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Prog

Contribution from Michael B. Porter, Jan 30 2010: (Start)
(PARI) A033676(n) = {local(d); if(n<2, 1, d=divisors(n); d[(length(d)+1)\2])}
A072489(n) = if(n<2, 1, n*A072489(n-1)/A033676(n))
a=1; print(a); for(n=2, 20, a=n*a/A033676(n); print(a)) (End)

Crossrefs

Cf. A072488.

Sequence in context: A104350 A328522 A220027 * A072487 A309875 A254232

Adjacent sequences: A072486 A072487 A072488 * A072490 A072491 A072492

Keyword

nonn

Author

Amarnath Murthy, Jul 13 2002

Status

approved