
EXAMPLE

Sum of pairs of digits of 12345=45+23+(0)1=69
The terms of this sequence can be found with a sieve:
n=1 to 99 > doubling > 2,4,6,8,10,...,196,198
n=100 to 199 > 101, 103, 105, ... , 199, 201, ... , 297, 299
n=200 to 299 > 202, 204, 206, 208, ... , 398, 400
n=300 to 303 > 303, 305, 307, 309
n=1 to 303 (sorted) > 2, 4, 6, ..., 96, 98, 100, 101, 102, 103, ..., 197, 198, 199, 201, 202, 203, 204, 205, ...,297, 298, 299, 300, 302, 303, 304, 305, 306, 307, 308, 309, 310, 312, 314, 316, 318, 320, 322, ..., 398, 400
The numbers < 304 that are missing are the terms of this sequence: 1, 3, 5, 7, ..., 97, 99, 200, 301
