A238120 - OEIS

%I #9 Feb 19 2014 21:27:49

%S 9,3528,12168,51984,207576,450241,711828,798768,1590121,7154784,

%T 8609599,40589641,95355225,138393792,244293408,344157184,726887051,

%U 737461269,1232922769,1290821184,1630544400,1734139449,2901360600,3002319675,3401256943,4435426801,4589212453

%N Powerful numbers of the form x^3 + y^3 with x and y coprime.

%C Powerful numbers are n such that p | n -> p^2 | n for all primes p, see A001694.

%H Charles R Greathouse IV, <a href="/A238120/b238120.txt">Table of n, a(n) for n = 1..150</a>

%o (PARI) list(lim)=my(v=List(),x3,t); for(x=1,sqrtnint(lim\1-1,3), x3=x^3; for(y=1,x, if(gcd(x,y)>1, next); t=x3+y^3; if(t>lim,break); if(ispowerful(t), listput(v,t)))); Set(v)

%Y Cf. A001694.

%K nonn

%O 1,1

%A _Charles R Greathouse IV_, Feb 17 2014