It also works with no zeros, or all sorts of other number of zeros. Dude basically just added zeros until the number got cooler.
The palindromic Belphegor numbers https://oeis.org/A232449
Indices of Belphegor primes: numbers k such that the decimal number https://oeis.org/A232448
The palindromic Belphegor numbers https://oeis.org/A232449
Indices of Belphegor primes: numbers k such that the decimal number https://oeis.org/A232448