Step 1: Divide the number into separate digits:
49941 => 4 9 9 4 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 9 => 5
9 to 9 => 0
9 to 4 => 5
4 to 1 => 3
1 to 4 => 3
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
5 => N
0 => E
5 => N
3 => N
3 => N
Step 4: Combine the filters to a string:
N E N N N = NENNN