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A325721
Start the sequence with a(1) = 1 and read the digits one by one from there. The sequence is always extended with the sum d + k, d being the digit read and k the number of d digits present so far in the sequence.
3
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 3, 1, 5, 4, 7, 6, 9, 8, 11, 10, 5, 6, 7, 2, 8, 9, 10, 4, 11, 12, 8, 3, 7, 9, 10, 11, 5, 12, 6, 11, 13, 12, 4, 13, 14, 9, 15, 6, 10, 16, 17, 18, 7, 19, 7, 8, 20, 8, 21, 9, 14, 22, 10, 11, 23, 5, 24, 12, 25, 12, 26, 13, 13, 27, 15, 14, 14, 8, 6, 15, 9, 28, 16, 29, 10, 10, 11, 30, 7, 31, 32, 12, 9, 11, 13, 11
OFFSET
1,2
EXAMPLE
The sequence starts with a(1) = 1.
We read this 1, see that there is only one digit 1 so far in the sequence, thus k = 1; we have then d + k = (1 + 1) = 2 and this 2 becomes a(2);
We read this 2, see that there is only one digit 2 so far in the sequence, thus k = 1; we have then d + k = (2 + 1) = 3 and this 3 becomes a(3);
We read this 3, see that there is only one digit 3 so far in the sequence, thus k = 1; we have then d + k = (3 + 1) = 4 and this 4 becomes a(4);
...
We now read the first digit of a(10) = 10, see that this 1 is the 2nd digit 1 so far in the sequence, thus k = 2; we have then d + k = (1 + 2) = 3 and this 3 becomes a(11);
We now read the second digit of a(10) = 10, see that this 0 is the 1st digit 0 so far in the sequence, thus k = 1; we have then d + k = 1 and this 1 becomes a(12);
We now read the single digit of a(11) = 3; we see that this 3 is the 2nd digit 3 so far in the sequence, thus k = 2; we have then d + k = 5 and this 5 becomes a(13); etc.
CROSSREFS
Cf. A325722 where the same idea is developed, but with d*k instead of d+k. See also A308232 for the concatenation kd.
Cf. A322182.
Sequence in context: A089898 A071785 A351868 * A079050 A320109 A278062
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, May 16 2019
STATUS
approved