Sum of Consecutive Triangular Numbers is Square/Historical Note

Historical Note on Sum of Consecutive Triangular Numbers is Square

According to David M. Burton, in his Elementary Number Theory, revised ed. of $1980$, this result has been attributed to Plutarch, circa $100$ C.E.

Sources

• 1980: David M. Burton: Elementary Number Theory (revised ed.) ... (previous) ... (next): Chapter $1$: Some Preliminary Considerations: $1.3$ Early Number Theory: Problems $1.3$: $1 \ \text {(c)}$