is(n) = { nf = n!; f = factor(nf); rf = cf = f; rf[, 2] = f[,2]%6; cf[, 2] = (f[,2] - rf[,2])\6; d = divisors(factorback(cf)); s = factorback(rf); for(i = 1, #d, if(isofform(s * d[i]^6), return(1); ) ); 0 } isofform(n) = {my(nf = n); \\print(n); for(i = 1, sqrtnint(nf, 6), for(j = 1, sqrtnint(nf - i^6, 3), if(issquare(nf - i^6 - j^3), return(1) ) ) ); 0 }