MathDB

7

Part of 1970 IMO Shortlist

Problems(1)

Find a such that each digit of n(n+1)/2 equals a

Source:

9/23/2010
For which digits aa do exist integers n≥4n \geq 4 such that each digit of n(n+1)2\frac{n(n+1)}{2} equals a ?a \ ?
modular arithmeticnumber theoryDigitsequationIMO Shortlist