This sequence is an obfuscation of a classic mathematical sequence...
The Fibonacci sequence, which begins $1$, $1$, $2$, $3$, $5$, $8$, $13$, $21$, $34$, ... with each term being the sum of the previous two.
The numbers in this string have been obtained by...
...taking each term of the Fibonacci sequence, dividing it by 6, cancelling down the numerator and denominator, presenting it as a 'mixed number' (i.e. the greatest whole number possible, with the remainder as a fraction), then concatenating all digits and removing the fraction bars.
This way...
$1$, $1$, $2$, $3$, $5$, $8$, $13$, $21$, ...
on dividing by 6, becomes:
$\frac16$, $\frac16$, $\frac26$, $\frac36$, $\frac56$, $\frac86$, $\frac{13}6$, $\frac{21}6$, ...
which, cancelling down the fractions, becomes:
$\frac16$, $\frac16$, $\frac13$, $\frac12$, $\frac56$, $\frac43$, $\frac{13}6$, $\frac72$, ...
which, presented as mixed numbers, becomes:
$\frac16$, $\frac16$, $\frac13$, $\frac12$, $\frac56$, $1\frac13$, $2\frac16$, $3\frac12$, ...
which, concatenated and with fraction bars removed, becomes:
1616131256113216312...
Here you can see that the numbers in bold in the string represent the whole number parts of the mixed numbers.
The next few digits in the string must therefore be derived by applying the same transformation to...
...the next term of the Fibonacci sequence: 34.
Since $\frac{34}6$ is $5\frac23$, these next digits will be 523.