0,2

a(m) = (x^(m+2)*(z-y)+y^(m+2)*(x-z)+z^(m+2)*(y-x))/((x-y)*(y-z)*(z-x))

a(2)=619 because sum(x^i*y^j*z^k)=x^2+y^2+z^2+x*y+x*z+y*z = 5^2+12^2+13^2+5*12+5*13+12*13 =619 and x^2+y^2=z^2

seq(sum(5^(m-n)*sum(12^p*13^(n-p), p=0..n), n=0..m), m=0..N);

Cf. A025942 A020000 A021664 A019682 A021684 A021844 A020340 A020341 A020342 A020344 A020345 A020346 A077515.

Adjacent sequences: A124096 A124097 A124098 this_sequence A124100 A124101 A124102

Sequence in context: A020980 A051303 A020975 this_sequence A028258 A075911 A001719

nonn

Giorgio Balzarotti and Paolo P. Lava (greenblue(AT)tiscali.it), Nov 26 2006