CREATE TABLE "table1_2159547_3" (
  "district" text,
  "vacator" text,
  "reason_for_change" text,
  "successor" text,
  "date_successor_seated" text
);

Question: On what date was James P. Buchanan (d)'s successor seated?
SQL: SELECT "date_successor_seated" FROM "table1_2159547_3" WHERE "vacator"='James P. Buchanan (D)';

Question: How many people vacated to successor Dave E. Satterfield, Jr. (d)?
SQL: SELECT COUNT("vacator") FROM "table1_2159547_3" WHERE "successor"='Dave E. Satterfield, Jr. (D)';

Question: Why did Robert L. Bacon (r) vacate?
SQL: SELECT "reason_for_change" FROM "table1_2159547_3" WHERE "vacator"='Robert L. Bacon (R)';