Crazy Sequential Representations - The 10958 Problem
2019-12-30, 11:55–12:00, Borg

CSR give integers in terms of 1 to 9 by using addition, subtraction, multiplication, division, exponentiation, parenthesis and/or digit concatenation.


Inder Taneja attempted to write the integers from 1 up to 11111 in terms of 1 to 9 by using addition, subtraction, multiplication, division, exponentiation, parenthesis and/or digit concatenation. For example:

9617 = 1+2^3*(45+(6+7)*89) 
9618 = 1*(2+3+4+5)*(678+9)
9619 = 1+(2+3+4+5)*(678+9)

These are generally referred to as crazy sequential representations (CSR). Interestingly, within the 1 up to 11111 range, only one CSR remains to be identified, namely the CSR for 10958.