A379054 a(n) = composite(2*n+2) - composite(2*n).

3, 3, 3, 3, 3, 3, 2, 2, 4, 2, 2, 3, 3, 3, 3, 2, 2, 3, 2, 3, 3, 2, 3, 2, 4, 2, 2, 3, 3, 2, 2, 3, 2, 2, 3, 2, 4, 2, 4, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 3, 2, 2, 2, 3, 3, 2, 3, 2, 2, 3, 3, 2, 2, 3, 2, 3, 3, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 3, 3, 3

Offset

1,1

Comments

A121053 is divided into blocks, and (ignoring the initial terms of A121053) these are the lengths of the blocks.

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Mathematica

Differences[Select[Range[300], CompositeQ][[2 ;; ;; 2]]] (* Paolo Xausa, Dec 18 2024 *)

Crossrefs

First differences of A099862.

Cf. A002808, A099861, A121053, A379055.

Sequence in context: A122845 A135203 A251552 * A324497 A179804 A368311

Adjacent sequences: A379051 A379052 A379053 * A379055 A379056 A379057

Keyword

nonn

Author

N. J. A. Sloane, Dec 18 2024

Status

approved