Slični zadaci

For which digits $a$ do exist integers $n \geq 4$ such that each digit of $\frac{n(n+1)}{2}$ equals $a \ ?$

Zadaci

#	Naslov	Oznake	Rj.
1343	IMO Shortlist 1969 problem 13	1969 shortlist tb	0
1345	IMO Shortlist 1969 problem 15	1969 shortlist tb	1
1348	IMO Shortlist 1969 problem 18	1969 shortlist tb	0
1353	IMO Shortlist 1969 problem 23	1969 shortlist tb	0
1354	IMO Shortlist 1969 problem 24	1969 shortlist tb	0
1355	IMO Shortlist 1969 problem 25	1969 shortlist tb	0

Školjka