A009129 - OEIS

A009129

Perimeter of more than one Pythagorean triangle.

60, 84, 90, 120, 132, 144, 168, 180, 210, 240, 252, 264, 270, 280, 288, 300, 312, 330, 336, 360, 390, 396, 408, 420, 432, 440, 450, 456, 462, 468, 480, 504, 510, 520, 528, 540, 546, 552, 560, 570, 576, 588, 600, 612, 616, 624, 630, 660, 672, 680, 684, 690, 700, 720

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

PROG

(PARI) is(k)=my(m2, mm2, s); for(m=2, sqrtint(k\2), m2=2*m; mm2=2*m^2; forstep(n=if(m%2, 2, 1), min(k\m2-m, m-1), m%2+1, if(k%(mm2+m2*n)==0 && gcd(m, n)==1 && s++>1, return(1)))); 0 \\ Charles R Greathouse IV, Feb 03 2018

(PARI) list(lim)=my(v=List(), ct=Map(), m2, mm2, t); for(m=2, sqrtint(lim\2), m2=2*m; mm2=2*m^2; forstep(n=if(m%2, 2, 1), min(lim\m2-m, m-1), m%2+1, if(gcd(m, n)>1, next); t=mm2+m2*n; forstep(k=t, lim, t, mapput(ct, k, mapisdefined(ct, k))))); for(n=60, lim, if(mapisdefined(ct, n) && mapget(ct, n), listput(v, n))); ct=0; Vec(v) \\ Charles R Greathouse IV, Feb 03 2018

CROSSREFS

Subsequence of A010814.

Sequence in context: A178212 A182855 A350371 * A174292 A085987 A356413

Adjacent sequences: A009126 A009127 A009128 * A009130 A009131 A009132

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved