A144672 - OEIS

A144672

Numbers x,y,z such that UnitarySigma(x) = UnitarySigma(y) = UnitarySigma(z) = 3*(x*y*z)^(1/2)/(- x^(1/2) + 8*y^(1/2) - 5*z^(1/2)), z<=y<=x; sequence gives x.

2, 20, 24, 360, 816, 1056, 12240, 15840, 29120, 181632, 337977, 2724480, 93358848, 1400382720

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OFFSET

1,1

COMMENTS

a(11) is the smallest term for x!=y, y!=z, x!=z.

If x=y=z then we get multiply unitary perfect numbers such that UnitarySigma(x)=3x/2.

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

Factorization of a(11) : 17*3^2*47^2.

CROSSREFS

Cf. A034448, A144673, A144674 (these entries all differ at a(11)).

Sequence in context: A196748 A144674 A144673 * A145681 A108061 A154546

Adjacent sequences: A144669 A144670 A144671 * A144673 A144674 A144675

KEYWORD

nonn,more

AUTHOR

Yasutoshi Kohmoto, Feb 02 2009

STATUS

approved