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A136742 Product of the n-th run of squarefree numbers. 7
6, 210, 110, 2730, 17, 19, 10626, 26, 26970, 39270, 54834, 74046, 2162, 51, 53, 55, 195054, 3782, 287430, 342930, 5402, 474474, 6806, 635970, 89, 91, 830490, 97, 1061106, 1190910, 1330890, 1481430, 14042, 15006, 127, 2196870, 17822, 2627934 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are squarefree;

a(n) mod A072284(n) = 0;

A136743(n) = A001221(a(n)).

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Squarefree

FORMULA

a(n) = Product_{k=0..A120992(n)-1} (A072284(n)+k).

EXAMPLE

n=10: A072284(10)=33, A120992(10)=3: a(10)=33*34*35=39270.

MAPLE

R:= NULL:

state:= false:

count:= 0:

for n from 1 while count < 100 do

if numtheory:-issqrfree(n) then

     if state then P:= P*n

     else P:= n; state:= true

     fi

  elif state then

     R:= R, P;

     count:= count+1;

     state:= false

  fi

od:

R; # Robert Israel, Jan 06 2020

MATHEMATICA

Times @@ # & /@ DeleteCases[#, _?(! SquareFreeQ@ First@ # &)] &@ SplitBy[Range[140], SquareFreeQ] (* Michael De Vlieger, Jan 06 2020 *)

CROSSREFS

Cf. A005117.

Sequence in context: A172530 A201237 A120436 * A334285 A068969 A335715

Adjacent sequences:  A136739 A136740 A136741 * A136743 A136744 A136745

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jan 20 2008

STATUS

approved

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Last modified August 10 13:30 EDT 2020. Contains 336381 sequences. (Running on oeis4.)