padicappr(x,O(2))
padicappr(x^2+1+O(3), Mod(-1+O(5^10),y^2-2))
padicappr(x^2+1+O(3), -1+O(5^10))
test(p, e = 1)=
{ my (N = 7*p^2);
  for (i=0,10,if (!ispower(i+O(p^e), N), print([i,p,e])));
  for (i=1,10,if (!ispower((i+O(p^e))^N, N), error([i,p,e])));
}
test(2)
test(2,2)
test(2,3)
test(3)
test(3,3)
test(11,3)
test(nextprime(2^64),3)
