A379692 a(1) = 1; a(n) is the most recently occurring value not among the last k terms where k is the number of times a(n-1) has occurred; if no such value exists, a(n) is the smallest unused positive integer.

1, 2, 1, 3, 1, 2, 3, 1, 4, 1, 5, 1, 2, 4, 1, 3, 2, 5, 3, 1, 6, 1, 7, 1, 4, 6, 1, 8, 1, 2, 4, 6, 1, 3, 8, 1, 5, 3, 6, 8, 5, 1, 7, 5, 6, 8, 1, 4, 7, 8, 6, 5, 3, 2, 4, 7, 5, 8, 6, 1, 9, 1, 10, 1, 11, 1, 12, 1, 13, 1, 14, 1, 15, 1, 16, 1, 17, 1, 18, 1, 3, 15, 1, 4

Offset: 1

Author

Neal Gersh Tolunsky, Dec 29 2024

Keywords

• nonn

Comments

The number preceding and following each first occurrence is the same (with the exception of a(1)=1 which has no predecessor).

Examples

			To find a(14)=4, we see that a(13) = 2 has occurred 3 times in the sequence, so the most recently occurring value before (5, 1, 2) which is not equal to 5,1,2 is a(9) = 4, so a(14) = 4.
		

Links

• Neal Gersh Tolunsky, Table of n, a(n) for n = 1..10000
• Neal Gersh Tolunsky, Graph of 100000 terms
• Neal Gersh Tolunsky, Ordinal transform of 200000 terms
• Neal Gersh Tolunsky, Graph of 400000 terms

Crossrefs

Cf. A358921.