A number

is said to be
tcefrep (which is
perfect spelled backwards) if

is equal to

plus its reverse.
For example,
is a tcefrep number since
The tcefrep numbers up to
are
6, 498906, 20671542, 41673714, 73687923, 4158499614, 922964834547.
Pictorial representation of remainders (mod 2, 3, ...,11) frequency. For a table of values and more details
click here