A365939 Gilbreath transform of semiprimes (A001358).

4, 2, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1

Offset

1,1

Links

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

Index entries for sequences related to Gilbreath conjecture and transform

Mathematica

A365939list[upto_]:=If[upto<4, {}, Module[{d=Select[Range[upto], PrimeOmega[#]==2&]}, Join[{4}, Table[First[d=Abs[Differences[d]]], Length[d]-1]]]]; A365939list[500] (* Paolo Xausa, Sep 25 2023 *)

Crossrefs

Leading terms of rows of the array in A131749.

Cf. A001358, A196251, A361897, A362451.

Sequence in context: A113092 A033324 A266145 * A266144 A016508 A351986

Adjacent sequences: A365936 A365937 A365938 * A365940 A365941 A365942

Keyword

nonn

Author

N. J. A. Sloane, Sep 25 2023.

Extensions

More terms from Pontus von Brömssen, Sep 25 2023

Status

approved