A038596 - OEIS

%I #14 Nov 01 2013 09:30:02

%S 169,784,2401,10816,21609,32761,35721,50176,123201,130321,150544,

%T 153664,257049,301401,345744,456976,571536,692224,1058841,1382976,

%U 1750329,1874161,2030625,2096704,2286144,2640625,3211264,3467044,3651921,3694084,5285401,5546025

%N Squares that are a difference between 2 positive cubes.

%H Donovan Johnson, <a href="/A038596/b038596.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A038597(n)^2. - _M. F. Hasler_, Oct 05 2013

%o (PARI) is(n)=for(k=sqrtnint(n,3)+1,(sqrtint(12*n-3)+3)\6,if(ispower(n-k^3,3), return(issquare(n)))); 0 \\ _Charles R Greathouse IV_, Oct 28 2013

%o (PARI) mm=820188; cb=vector(mm); for(i=1, mm, cb[i]=i^3); mb=1420608; v=vector(mb); mx=mb^2; for(i=1, mm-1, for(j=i+1, mm, d=cb[j]-cb[i]; if(d<=mx, if(issquare(d, &r), v[r]=1), next(2)))); c=0; for(n=1, mb, if(v[n]==1, c++; write("b038596.txt", c " " n^2))) \\ _Donovan Johnson_, Oct 31 2013

%Y Cf. A038593-A038598.

%K nonn

%O 1,1

%A _Jeff Burch_

%E More terms from _Jud McCranie_