Choose the vowel for position #1, which is odd, as any of the 3 vowels,
{E,O,U}.
Choose the vowel for position #3, which is odd, as either of the
2 remaining vowels.
Choose the vowel for position #5, which is odd, as the only 1 remaining
vowel.
Choose the consonant for position #2 as any of the 3 consonants,
{C,R,S}.
Choose the consonant for position #4, as either of the 2 remaining
consonants.
Choose the consonant for position #6, as the only 1 remaining
only remaining consonant.
That's 3*2*1*3*2*1 = 36 ways. Here are all 36 listed below, in
alphabetical order. Pick any 4.
1. ECORUS
2. ECOSUR
3. ECUROS
4. ECUSOR
5. EROCUS
6. EROSUC
7. ERUCOS
8. ERUSOC
9. ESOCUR
10. ESORUC
11. ESUCOR
12. ESUROC
13. OCERUS
14. OCESUR
15. OCURES
16. OCUSER
17. ORECUS
18. ORESUC
19. ORUCES
20. ORUSEC
21. OSECUR
22. OSERUC
23. OSUCER
24. OSUREC
25. UCEROS
26. UCESOR
27. UCORES
28. UCOSER
29. URECOS
30. URESOC
31. UROCES
32. UROSEC
33. USECOR
34. USEROC
35. USOCER
36. USOREC
Edwin