INTERNATIONAL CONTEST OF LOGICAL SEQUENCES 2002 – 2003

Albert Frank

The following series need very few mathematical knowledge and are culture free. Some are extremely difficult. Each answer has to be clearly explained, in English or in French. The solutions must be send before March 1st 2003, by e-mail (with subject « International contest 2002 – 2003 ») to albert.frank@skynet.be or by mail:

Albert Frank
13 Clos du Parnasse / box 45
1050 Brussels
BELGIUM

Good luck !

  1. 2, 6, 15, ?, 55, ?, 119
  2. 4, ?, 5, 2, 6, 10, 3, 7, 6
  3. 1, 3, 9, 9, 9, 9, 18, 18, 18, 27, 27, ?, ?
  4. 0, 0, 2, 0, 2, 4, 2, 0, ?, ?
  5. 6, 3, 20, 7, ?, 117, ?, 114
  6. 6, 7, 2, 1, 5, 9, ?, ?, ?
  7. ?, -1, -1, -1, 0, 2, 6, 13, 25, ?
  8. 2614534, 4?45??
  9. 1, 2, 3, 5, 8, 10, ?, 16, 23
  10. 1010, 202, 132, 130, 122, 114, 106, ?, 90
  11. 4, 9, 7, 13, ?, 16, 19, ?, 16, 13
  12. Why are there two * in this finite sequence?
    1, 5, 9, 6, 3, *, 2, 4, *, 7, 8, 9
  13. 5, 6, 7, 8, 8, 8, 8, ?, ?
  14. 4, 6, 10, ?, 3, 7, 15, 19, 11, ?
  15. 6, 14, 6, 5, 40, 90, 104, ?
  16. -1, -1, 1, 17, 109, 707, ?
  17. 1, 2, 3, 6, ?, 6, 3, 6, 1
  18. 0, 1, 2, 3, 1, 1, ?, 3, ?, 9
  19. 11, 23, 44, 56, 48, 67, ?
  20. 1, 2, 2, 1, 2, 4, 2, 2, 1, 2, ?, 2, 2, 1, 2, 2, 2, ?, 2, 1