Which Frequency MHz is the highest one that has a Call sign of k241an?
CREATE TABLE "translators" (
  "call_sign" text,
  "frequency_m_hz" real,
  "city_of_license" text,
  "erp_w" real,
  "class" text,
  "fcc_info" text
);
SELECT MAX("frequency_m_hz") FROM "translators" WHERE "call_sign"='k241an';