A383339 a(1)=1; thereafter if a(n-1) is a first occurrence, then a(n) is the number of first occurrences in the sequence thus far. Otherwise; a(n) is the number of terms that are the same distance away from their previous last occurrence as a(n-1).

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

Offset

1,4

Comments

Alternatively, a(n) is the number of terms with the same Backwards van Eck transform as a(n-1).

Links

Neal Gersh Tolunsky, Table of n, a(n) for n = 1..10000

Neal Gersh Tolunsky, Backwards van Eck transform of the first 400000 terms

Neal Gersh Tolunsky, Graph of the first 400000 terms

Example

a(14) = 5: a(13) = 2 has a distance of 1 from its previous last occurrence a(12) = 2. There are 5 terms in total with a distance of 1 from their previous last occurrence; they are at indices i = 2,3,6,10,13. So a(14) = 5.

Crossrefs

Cf. A383340, A383421.

Sequence in context: A025474 A136575 A309898 * A193592 A243714 A343656

Adjacent sequences: A383336 A383337 A383338 * A383340 A383341 A383342

Keyword

nonn

Author

Neal Gersh Tolunsky, Apr 23 2025

Status

approved