A066851 - OEIS

A066851

Number of ordered solutions (x,y,z) to xy + yz + zx = n with x,y,z >= 1.

0, 0, 1, 0, 3, 0, 3, 3, 3, 0, 9, 1, 3, 6, 6, 3, 9, 0, 9, 9, 6, 0, 15, 6, 3, 12, 10, 3, 15, 0, 15, 12, 6, 6, 18, 9, 3, 12, 18, 6, 21, 0, 9, 21, 9, 6, 27, 7, 9, 12, 18, 9, 15, 12, 18, 24, 6, 0, 33, 6, 15, 18, 21, 12, 18, 12, 9, 27, 18, 0, 39, 9, 9, 24, 19, 21, 18, 0, 27, 27, 18, 6, 33, 18, 6

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,5

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..10000 (terms 1..1000 from T. D. Noe)

EXAMPLE

a(5) = 3 since there are solutions (2,1,1), (1,2,1), (1,1,2).

PROG

(PARI) a(n) = sum(x=1, n-2, sum(y=1, (n-2)\x, (n-x*y)%(x+y)==0 )) \\ Andrew Howroyd, Oct 31 2025

CROSSREFS

a(A025052(n))=0. Cf. A066958.

Sequence in context: A375064 A066958 A357062 * A288571 A270028 A167223

Adjacent sequences: A066848 A066849 A066850 * A066852 A066853 A066854

KEYWORD

easy,nonn

AUTHOR

Colin Mallows, Jan 24 2002

EXTENSIONS

More terms from Vladeta Jovovic, Jan 25 2002

STATUS

approved