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A169900 Earliest sequence such that xy | a(x+y) for all x>=1, y>=1. 0
1, 1, 2, 12, 12, 360, 60, 1680, 2520, 25200, 2520, 332640, 27720, 5045040, 5405400, 2882880, 720720, 220540320, 12252240, 4655851200, 4888643760, 5121436320, 232792560, 128501493120, 26771144400, 696049754400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

After a(1)=a(2)=1, we must have a(3) >= 2 from 2 | a(1+2), and a(3)=2 works.

MATHEMATICA

a[n_]:=If[n<=2, 1, LCM@@Table[x(n-x), {x, Floor[n/2]}]]; Table[a[n], {n, 30}] [From Zak Seidov, Jul 11 2010]

CROSSREFS

Sequence in context: A198477 A075178 A145618 * A140355 A007041 A028424

Adjacent sequences:  A169897 A169898 A169899 * A169901 A169902 A169903

KEYWORD

nonn,nice

AUTHOR

Andrew Weimholt, Jul 05 2010

STATUS

approved

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Last modified May 23 08:03 EDT 2017. Contains 286909 sequences.