Palindromic Triangular Numbers/Mistake 1

Source Work

 * The Dictionary
 * $15$
 * $15$

Mistake

 * There are $40$ palindromic triangular numbers below $10^7$.

Correction
There are in fact $22$ of them below $10^7$.

The $23$rd one is $35 \, 133 \, 153$, which is $3 \cdotp 5 \times 10^7$.

In, this statement has been removed.