A072489 - OEIS

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A072489

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

2

1, 2, 6, 12, 60, 180, 1260, 5040, 15120, 75600, 831600, 3326400, 43243200, 302702400, 1513512000, 6054048000, 102918816000, 617512896000, 11732745024000, 58663725120000, 410646075840000, 4517106834240000, 103893457187520000, 623360743125120000

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..24.

FORMULA

a(n) = a(n-1) * A033677(n), n > 1. - Sean A. Irvine, Oct 04 2024

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. A033677, 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

EXTENSIONS

More terms from Sean A. Irvine, Oct 04 2024

STATUS

approved