A071819 a(n) is the difference between the two smallest positive integers that you cannot obtain using the integers {1,2,...,n} at most once and the four operators +, -, *, /.
1, 1, 1, 2, 3, 23, 5, 144, 98, 658
Offset: 1
Examples
a(4)=2 because 29 and 31 are the smallest numbers that you cannot obtain using {1,2,3,4} and the four operations and 31-29 = 2.
Links
- Gilles Bannay, Countdown Problem
- Index entries for similar sequences
Crossrefs
Cf. A060315.