Sum of 4 Consecutive Binomial Coefficients forming Square/Mistake
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Source Work
1997: David Wells: Curious and Interesting Numbers (2nd ed.):
- The Dictionary
- $767$
Mistake
Mistake $1$:
- $\dbinom {767} 1 + \dbinom {767} 2 + \dbinom {767} 3 + \dbinom {767} 4$ is a perfect square, $8672^2$.
Mistake $2$:
- The smaller solutions are $7$, $15$ and $74$.
Correction
The first mistake is that it is $\dbinom {767} 0 + \dbinom {767} 1 + \dbinom {767} 2 + \dbinom {767} 3 = 8672^2$.
The second mistake is that the numbers $-1$, $0$ and $2$ have the same property.
Wells is perhaps excused the first two, as they may not have been in his purview, but omitting $2$ is a less forgivable oversight, considering the complete set is given in 1994: Richard K. Guy: Unsolved Problems in Number Theory (2nd ed.), which he himself references.
Sources
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $767$