How many integers from 1 to 40 can you form using all 4 digits 2, 0, 1, and 7 exactly once each; the operators +, –, ×, /, ^, concatenation and ! ?

Any number of parenthesis may be used.

Examples: 1=217^0;
2=2+0*17;
3=21/7+0
...

etc

Team work (adding so far unresolved numbers ) encouraged.

4=7-2-1-0

5=7-2+1*0

6=7-2+1+0

7=7+(1+2)*0

8=7+2-1+0

9=7+2+1*0

10=7+2+1-0

11=7+2+1+0!

12=7*2-1-0!

13=7*2-1-0

14=7*2-1*0

15=7*2+1-0

16=(1+7)*2-0

17=17+2*0

18=17+2-0!

19=17+2-0

20=17+2+0!

21=21+7*0

22=21+(0!)^7

23=17+(2+0!)!

Posted by chun on 2017-06-23 14:20:10