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A139131 Squarefree kernel of n*(n+1)/2. 4
1, 3, 6, 10, 15, 21, 14, 6, 15, 55, 66, 78, 91, 105, 30, 34, 51, 57, 190, 210, 231, 253, 138, 30, 65, 39, 42, 406, 435, 465, 62, 66, 561, 595, 210, 222, 703, 741, 390, 410, 861, 903, 946, 330, 345, 1081, 282, 42, 35, 255, 1326, 1378, 159, 165, 770, 798, 1653, 1711 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A007947(A000217(n));

a(A014601(n)) = A078636(A014601(n));

a(n) = A078636(n) / A014695(n).

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..1000

MATHEMATICA

Times@@(Transpose[FactorInteger[#]][[1]])&/@Accumulate[Range[60]] (* Harvey P. Dale, Jun 06 2013 *)

CROSSREFS

Sequence in context: A096895 A034175 A306698 * A130485 A115015 A231676

Adjacent sequences:  A139128 A139129 A139130 * A139132 A139133 A139134

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Apr 10 2008

STATUS

approved

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Last modified July 28 00:54 EDT 2021. Contains 346316 sequences. (Running on oeis4.)