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 A051584 Number of integer-sided triangles of area n. 5
 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,12 COMMENTS If integer-sided triangle has integer area, area is divisible by 6. LINKS Antti Karttunen, Table of n, a(n) for n = 1..10085 PROG (PARI) A051585(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))); \\ From A051585 by Charles R Greathouse IV A051584(n) = if((n%6), 0, A051585(n/6)); \\ Antti Karttunen, Aug 23 2019 CROSSREFS Cf. A051585, A051586. Sequence in context: A028661 A028714 A028653 * A028645 A028710 A178926 Adjacent sequences:  A051581 A051582 A051583 * A051585 A051586 A051587 KEYWORD nonn AUTHOR EXTENSIONS Data section extended up to a(120) by Antti Karttunen, Aug 23 2019 STATUS approved

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Last modified June 25 03:59 EDT 2022. Contains 354835 sequences. (Running on oeis4.)