A091237 - OEIS

A091237

Lengths of runs in A039702.

1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 1, 1, 1, 2, 1, 2, 3, 2, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 4, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 2, 4, 1, 1, 1, 1, 2, 3, 7, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 3, 2, 2, 2, 1, 3, 4

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OFFSET

1,4

COMMENTS

Lengths of runs, where a run is a succession of primes that are congruent mod 4.

In other words, RUNS transform of A039702. If the two initial 1's are omitted, this is the RUNS transform of A100672. - N. J. A. Sloane, Jan 11 2025

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

MATHEMATICA

Most[Length /@ Split[Table[Mod[Prime[n], 4], {n, 200}]]] (* T. D. Noe, Sep 21 2012 *)

CROSSREFS

Cf. A039702, A091318, A091267, A100672.