|
|
A238120
|
|
Powerful numbers of the form x^3 + y^3 with x and y coprime.
|
|
1
|
|
|
9, 3528, 12168, 51984, 207576, 450241, 711828, 798768, 1590121, 7154784, 8609599, 40589641, 95355225, 138393792, 244293408, 344157184, 726887051, 737461269, 1232922769, 1290821184, 1630544400, 1734139449, 2901360600, 3002319675, 3401256943, 4435426801, 4589212453
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Powerful numbers are n such that p | n -> p^2 | n for all primes p, see A001694.
|
|
LINKS
|
|
|
PROG
|
(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)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|