A119794 - OEIS

A119794

a(n) is the product of the positive integers each of which is <= n and is divisible by exactly one prime dividing n (but is coprime to every other prime dividing n). (a(1) = 1).

1, 2, 3, 8, 5, 24, 7, 384, 162, 1920, 11, 17280, 13, 322560, 97200, 10321920, 17, 58060800, 19, 1393459200, 51438240, 40874803200, 23, 536481792000, 375000, 25505877196800, 7142567040, 535623421132800, 29, 439378587648000, 31

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OFFSET

1,2

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..807

EXAMPLE

12 is divisible by 2 and 3. The positive integers which are <= 12 and which are divisible by 2 or 3, but not by both 2 and 3, are: 2, 3, 4, 8, 9, 10. a(12) = the product of these integers, which is 17280.

MATHEMATICA

Table[Times @@ Select[Range@ n, Function[k, Total@ Boole@ Map[Divisible[k, #] &, FactorInteger[n][[All, 1]]] == 1]], {n, 31}] (* Michael De Vlieger, Oct 01 2017 *)

CROSSREFS

Cf. A116512, A119790, A120499.

Sequence in context: A333375 A289667 A053650 * A117987 A376016 A091136

Adjacent sequences: A119791 A119792 A119793 * A119795 A119796 A119797

KEYWORD

nonn

AUTHOR

Leroy Quet, Jul 30 2006

EXTENSIONS

Corrected and extended by Joshua Zucker, Aug 12 2006

STATUS

approved