\\ Very crude script demonstrating a factorization-free method of computing terms of the sequence.
\\ Compute the requested term of A190880.
a(n,lim=25000)={
local(v=List());
foralmostprime(2,lim,n,u->
if(is(u),
listput(v,vecprod(u))
)
);
v=vecsort(Vec(v));
if(#v,
v[1]
,
print("Testing up to ", lim<<=1);
a(n,lim)
)
};
\\ Is k divisible by the square of the sum of its prime divisors, where v is a vector of the prime power factorization of k?
is(v)={
my(t);
vecprod(v)%sum(i=1,#v,t=v[i];ispower(t,,&t);t)^2==0
};
\\ Loop over prime powers (not in order).
forpp(a,b,ff)={
my(t);
forprime(p=2,sqrt(b),t=p;while(t1,
for(i=1,#v-1,
if(gcd(v[i],v[#v])!=1, return())
)
);
for(i=1,#v,newV[i]=v[i]);
if (k > 1,
if(#v,
forpp(v[#v]+1,b^(1/k),p->
newV[#newV]=p;
foralmostprime(max(p+1,a\p), b\p, newK, ff, newV)
)
,
forpp(2,b^(1/k),p->
newV[#newV]=p;
foralmostprime(max(p+1,a\p), b\p, newK, ff, newV)
)
)
,
my(t);
forprime(p=2,sqrt(b),
for(i=1,#v,if(v[i]%p==0, next(2)));
t=p;
while(t