A317922 a(n) = number of k with 0 < 2*k < n-1 such that a(n-k) AND a(n-2*k) = a(n-k) (where AND denotes the bitwise AND operator).

0, 0, 1, 0, 1, 1, 3, 0, 2, 1, 2, 1, 3, 3, 4, 0, 3, 2, 4, 2, 4, 3, 5, 1, 3, 3, 7, 2, 4, 4, 7, 0, 4, 3, 6, 5, 7, 4, 8, 2, 6, 4, 12, 1, 10, 5, 7, 2, 7, 1, 9, 3, 5, 6, 9, 4, 7, 3, 7, 3, 11, 5, 8, 3, 8, 4, 10, 3, 11, 6, 11, 1, 9, 4, 11, 8, 10, 8, 13, 2, 11, 7, 15

Offset

1,7

Comments

This sequence has similarities with A317420.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..50000

Rémy Sigrist, Scatterplot of the first 10000000 terms

Rémy Sigrist, Colored scatterplot of the first 10000000 terms (where the color is function of the 2-adic valuation of n (A001511))

Rémy Sigrist, Colored scatterplot of the first 10000000 terms (where the color is function of A000265(n) mod 16)

Rémy Sigrist, C++ program for A317922

Example

For n = 5:
- a(5-1) AND a(5-2) = 0 AND 1 = 0 = a(5-1),
- a(5-2) AND a(5-4) = 1 AND 0 = 0 <> a(5-2),
- hence a(5) = 1.

Prog

(C++) See Links section.

Crossrefs

Cf. A000265, A001511, A317420.

Sequence in context: A021335 A089595 A238133 * A337320 A194808 A329204

Adjacent sequences: A317919 A317920 A317921 * A317923 A317924 A317925

Keyword

nonn,base

Author

Rémy Sigrist, Aug 11 2018

Status

approved