A038597 - OEIS

%I #17 Jun 20 2021 08:26:52

%S 13,28,49,104,147,181,189,224,351,361,388,392,507,549,588,676,756,832,

%T 1029,1176,1323,1369,1425,1448,1512,1625,1792,1862,1911,1922,2299,

%U 2355,2521,2808,2883,2888,3104,3136,3185,3216,3500,3721,3969,4056,4103,4332

%N Numbers whose square is a difference between 2 positive cubes in at least one way.

%H Donovan Johnson, <a href="/A038597/b038597.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = sqrt(A038596(n)). - _M. F. Hasler_, Oct 05 2013

%o (PARI) is(n)=my(N=n^2); for(k=sqrtnint(N,3)+1,(sqrtint(12*N-3)+3)\6, if(ispower(N-k^3,3), return(1))); 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("b038597.txt", c " " n))) \\ _Donovan Johnson_, Oct 31 2013

%Y Cf. A038593-A038598.

%K nonn

%O 1,1

%A _Jeff Burch_

%E More terms from _Jud McCranie_