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A051585 Number of integer-sided triangles of area 6n. 6
1, 2, 0, 2, 1, 2, 1, 2, 1, 4, 1, 1, 0, 4, 2, 2, 0, 2, 1, 4, 3, 1, 0, 2, 1, 2, 0, 4, 0, 2, 0, 2, 1, 1, 6, 3, 0, 0, 1, 5, 0, 3, 0, 3, 2, 0, 0, 2, 1, 4, 1, 0, 0, 2, 4, 8, 0, 0, 0, 5, 0, 0, 1, 2, 1, 3, 0, 1, 0, 15, 0, 2, 0, 0, 0, 4, 2, 1, 0, 5, 1, 0, 0, 6, 2, 0, 1, 3, 0, 4, 3, 0, 0, 0, 1, 2, 0, 2, 1, 2, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

If integer-sided triangle has integer area, area is divisible by 6.

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000

PROG

(PARI) a(n)=sum(z=sqrtint(sqrtint(192*n^2)-1)+1, sqrtint(9*(64*n^2+5)\20), sum(y=z\2+1, z, my(t=(y*z)^2-(12*n)^2, x); if(issquare(t, &t), (issquare(y^2+z^2-2*t, &x) && x<=y) + (t && issquare(y^2+z^2+2*t, &x) && x<=y), 0))) \\ Charles R Greathouse IV, Jun 27 2013

CROSSREFS

Cf. A051584, A051586.

Sequence in context: A107455 A039701 A025822 * A049115 A294204 A329697

Adjacent sequences:  A051582 A051583 A051584 * A051586 A051587 A051588

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 2 09:22 EDT 2021. Contains 346422 sequences. (Running on oeis4.)