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A120690 Number of ordered finite sequences a_1 <= a_2 <= ... <= a_n of length n of positive integers less than or equal to n whose product is n!. 1
1, 1, 1, 2, 2, 6, 6, 13, 33, 97, 97, 306, 306, 896, 2804, 7974, 7974, 24929, 24929, 82612, 263913, 782310, 782310 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

a(5)=2 because 5! = 1*2*3*4*5 = 2*2*2*3*5

PROG

(PARI) a(n) = (b(c, p, m) = local(x); if(c<=0||m<=1||p>m^c, p==1, x=valuation(p, m); sum(i=x*isprime(m), x, b(c-i, p/m^i, m-1)))); b(n, n!, n)

CROSSREFS

Cf. A119551.

Sequence in context: A337735 A060549 A228315 * A165124 A288302 A286409

Adjacent sequences:  A120687 A120688 A120689 * A120691 A120692 A120693

KEYWORD

more,nonn

AUTHOR

Martin Fuller, Jun 26 2006

STATUS

approved

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Last modified October 22 16:15 EDT 2021. Contains 348174 sequences. (Running on oeis4.)