[seqfan] Inside differences

[Eric Angelini]

Hello SeqFans,

Pick any term T of S and underline any digit of T;
this underlined digit is the difference between two
not-underlined digits of T:

S = 101, 110, 202, 220, 303, 330, 404, 440, 505, 550, 606, 660, 707, 770, 808, 880, 909, 990, 1001, 1010, 1100, 2002, 2020, 2200, 3003, 3030, 3300, 4004, 4040, 4400, 5005, 5050, 5500, 6006, 6060, 6600, 7007, 7070, 7700, 8008, 8080, 8800, 9009, 9090, 9900, 10001, 10010, 10011, 10100, 10101, 10110, 10111, 10122, 10212, 10221, 11000, 11001, 11010, 11011, 11022, 11100, 11101, 11110, 11202, 11220, 12012, 12021, 12102, 12120, 12201, 12210,...

I guess the first such pandigital to appear is 10234567899.

If we are allowed to re-use the underlined digit in the
difference itself, then we'll get U:

U = 100, 101, 110, 200, 202, 220, 300, 303, 330, 400, 404, 440, 500, 505, 550, 600, 606, 660, 700, 707, 770, 800, 808, 880, 900, 909, 990, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009, 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, 1019, 1020, 1021, 1022, 1030, 1031, 1033,... 

Example for 100: 
-- we underline "1" and "1" is 1-0 (we re-use the underlined "1" in the difference itself)
-- we underline "0" and "0" is 0-0 (we re-use the underlined "0" in the difference itself)

Best,
É.