A379055 a(n) = composite(2*n+3) - composite(2*n+1).

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

Offset: 0

Author

N. J. A. Sloane, Dec 18 2024

Keywords

• nonn

Links

• Paolo Xausa, Table of n, a(n) for n = 0..10000

Crossrefs

First differences of A099861.

Cf. A002808, A099861, A379054.

Programs

Mathematica

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