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A057229 a(n) = a*b = x*y with (a-b) = (x+y) = A020882(n) (a>b, a>0, b>0, x>0, y>0), gcd(a, b) = gcd(x, y) = 1. 2
6, 30, 60, 84, 210, 210, 180, 630, 330, 504, 924, 1320, 546, 1386, 1560, 2340, 990, 2730, 840, 2574, 4620, 1224, 1716, 3570, 5610, 7140, 4290, 1710, 5016, 7956, 7980, 2730, 7854, 10374, 2310, 11970, 6630, 10920, 12540, 4080, 3036, 11856, 8970 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

The quadratics in X, X^2 - S*X -+ P, where S=A020882(n), P=A057229(n) are each factorizable into two factors, all four being distinct: X^2 - S*X - P = (X - a)*(X + b). X^2 - S*X + P = (X - x)*(X - y). - Lekraj Beedassy, Apr 30 2004

Areas of primitive Pythagorean triangles sorted on hypotenuse A020882, then on perimeter A093507. - Lekraj Beedassy, Aug 18 2006

LINKS

Table of n, a(n) for n=0..42.

P. Yiu, Factorizable x^2 + px -+ q, Recreational Mathematics, pp. 58/360.

EXAMPLE

E.g. a(1)=6=6*1=3*2, (6-1)=(3+2)=5=A020882(1), gcd(6,1)=gcd(3,2)=1

CROSSREFS

Cf. A020882, A008846, A024406, A024365.

Sequence in context: A239978 A024406 A024365 * A120734 A116360 A336219

Adjacent sequences:  A057226 A057227 A057228 * A057230 A057231 A057232

KEYWORD

nonn

AUTHOR

Naohiro Nomoto, Sep 19 2000

STATUS

approved

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Last modified September 18 20:19 EDT 2020. Contains 337173 sequences. (Running on oeis4.)