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

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

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

Crossrefs

Subsequence of A010814.

Programs

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