A329257 a(n) is the number of numbers k such that a(n-2*k) = a(n-k) and 0 < n-2*k < n-k < n .

0, 0, 1, 0, 0, 2, 1, 1, 2, 0, 1, 1, 2, 1, 2, 3, 4, 1, 2, 2, 4, 1, 1, 3, 5, 1, 1, 3, 3, 3, 3, 8, 3, 5, 2, 4, 2, 4, 2, 4, 3, 4, 4, 5, 1, 4, 1, 2, 4, 4, 5, 3, 1, 5, 5, 3, 4, 5, 7, 3, 5, 3, 6, 8, 5, 2, 4, 8, 3, 0, 6, 8, 1, 3, 3, 10, 4, 4, 9, 4, 4, 7, 9, 5, 3, 4, 6

Offset

1,6

Links

Rémy Sigrist, Table of n, a(n) for n = 1..25000

Rémy Sigrist, C program for A329257

Rémy Sigrist, Colored scatterplot of the first 250000 terms (where the color denotes the parity of n)

Example

The first terms, alongside the corresponding k's, are:
  n    a(n)  k's
  ---  ----  ------------
    1     0  {}
    2     0  {}
    3     1  {1}
    4     0  {}
    5     0  {}
    6     2  {1, 2}
    7     1  {3}
    8     1  {3}
    9     2  {1, 4}
   10     0  {}
   11     1  {4}
   12     1  {3}
   13     2  {1, 5}
   14     1  {3}
   15     2  {4, 5}
   16     3  {2, 4, 6}
   17     4  {2, 3, 4, 5}

Prog

(C) See Links section.

Crossrefs

See A329310 and A329311 for similar sequences.

Cf. A317922.

Sequence in context: A109066 A079066 A157188 * A173266 A342149 A224326

Adjacent sequences: A329254 A329255 A329256 * A329258 A329259 A329260

Keyword

nonn,look

Author

Rémy Sigrist, Nov 09 2019

Status

approved