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A020883 Ordered long legs of primitive Pythagorean triangles. 44
4, 12, 15, 21, 24, 35, 40, 45, 55, 56, 60, 63, 72, 77, 80, 84, 91, 99, 105, 112, 117, 120, 132, 140, 143, 144, 153, 156, 165, 168, 171, 176, 180, 187, 195, 208, 209, 220, 221, 224, 231, 240, 247, 252, 253, 255, 260, 264, 272, 273, 275, 285, 288, 299, 304, 308, 312, 323 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Consider primitive Pythagorean triangles (A^2 + B^2 = C^2, (A, B) = 1, A < B); sequence gives values of B, sorted.

Any term in this sequence is given by f(m,n) = 2*m*n or g(m,n) = m^2 - n^2 where m and n are any two positive integers, m > 1, n < m, the greatest common divisor of m and n is 1, m and n are not both odd; e.g., f(m,n) = f(2,1) = 2*2*1 = 4. - Agola Kisira Odero, Apr 29 2016

All terms are composite. - Thomas Ordowski, Mar 12 2017

a(1) is the only power of 2. - Torlach Rush, Nov 08 2019

The first term appearing twice is 420 = a(75) = a(76) = A024410(1). - Giovanni Resta, Nov 11 2019

LINKS

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

Ron Knott, Pythagorean Triples and Online Calculators

CROSSREFS

Cf. A020882, A020884, A020885, A020886, A024354, A024410.

Sequence in context: A215011 A024353 A024354 * A002365 A212245 A046087

Adjacent sequences:  A020880 A020881 A020882 * A020884 A020885 A020886

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Extended and corrected by David W. Wilson

STATUS

approved

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Last modified July 3 23:25 EDT 2020. Contains 335419 sequences. (Running on oeis4.)