Step 1: Divide the number into separate digits:
41133 => 4 1 1 3 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 1 => 3
1 to 1 => 0
1 to 3 => 2
3 to 3 => 0
3 to 4 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
3 => N
0 => E
2 => N
0 => E
1 => C
Step 4: Combine the filters to a string:
N E N E C = NENEC