A110901 - OEIS

A110901

Product_{k=1..n} (A013929(k)), the product of the first n positive integers that are each divisible by at least one square >= 4.

4, 32, 288, 3456, 55296, 995328, 19906560, 477757440, 11943936000, 322486272000, 9029615616000, 288947699712000, 10402117189632000, 416084687585280000, 18307726253752320000, 823847681418854400000, 39544688708105011200000

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

Since 4, 8, 9 and 12 are the first 4 nonsquarefree positive integers, the fourth term of the sequence is 4*8*9*12 = 3456.

MATHEMATICA

Rest[ FoldList[ Times, 1, Select[ Range[2, 48], (Union[Last /@ FactorInteger[ # ]][[ -1]] > 1) == True &]]] (* Robert G. Wilson v *)

FoldList[Times, Select[Range[50], !SquareFreeQ[#]&]] (* Harvey P. Dale, Dec 31 2022 *)

PROG

(PARI) a=1; for(n=1, 48, if(!issquarefree(n), print1(a=a*n, ", ")))

CROSSREFS

Cf. A013929, A111059.

Sequence in context: A370160 A372464 A366663 * A295538 A256183 A000766

Adjacent sequences: A110898 A110899 A110900 * A110902 A110903 A110904

KEYWORD

nonn

AUTHOR

Leroy Quet, Oct 09 2005

EXTENSIONS

More terms from Klaus Brockhaus and Robert G. Wilson v, Oct 11 2005

STATUS

approved