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 A024364 Ordered perimeters of primitive Pythagorean triangles. 21
 12, 30, 40, 56, 70, 84, 90, 126, 132, 144, 154, 176, 182, 198, 208, 220, 234, 240, 260, 286, 306, 312, 330, 340, 374, 380, 390, 408, 418, 420, 442, 456, 462, 476, 494, 510, 532, 544, 546, 552, 570, 598, 608, 644, 646, 650, 672, 684, 690, 700 (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 perimeters A+B+C. n is in this sequence iff A070109(n)>0. This is a subset of A010814. For the corresponding primitive Pythagorean triples see A103606. - Wolfdieter Lang, Oct 06 2014 Any term in this sequence can be generated by f(m,n) = 2*m*(m+n), where m and n are positive coprime integers and m > 1, n < m, and m and n are not both odd. For example: f(2,1) = 2*2*(2+1) = 12. - Agola Kisira Odero, Apr 29 2016 LINKS Ron Knott, Pythagorean Triples and Online Calculators FORMULA a(n) = 2*A020886(n). MAPLE isA024364 := proc(an) local r::integer, s::integer ; for r from floor((an/4)^(1/2)) to floor((an/2)^(1/2)) do for s from r-1 to 1 by -2 do if 2*r*(r+s) = an and gcd(r, s) < 2 then RETURN(true) ; fi ; if 2*r*(r+s) < an then break ; fi ; od ; od : RETURN(false) ; end : for n from 2 to 400 do if isA024364(n) then printf("%d, ", n) ; fi ; od ; # R. J. Mathar, Jun 08 2006 MATHEMATICA lst={}; amx=99; Do[For[b=a+1, b<(a^2/2), c=(a^2+b^2)^(1/2); If[c==IntegerPart[c]&&GCD[a, b, c]==1, p=a+b+c; AppendTo[lst, p]]; b=b+2], {a, 3, amx}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 08 2008 *) CROSSREFS Cf. A020886. Sequence in context: A083096 A289691 A145469 * A093507 A145470 A108278 Adjacent sequences:  A024361 A024362 A024363 * A024365 A024366 A024367 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 23 02:13 EDT 2018. Contains 315271 sequences. (Running on oeis4.)