A156242 - OEIS

A156242

Bisection of A054353.

3, 6, 9, 12, 15, 19, 21, 24, 27, 30, 33, 36, 39, 42, 45, 47, 50, 54, 57, 60, 63, 66, 69, 72, 75, 77, 81, 84, 87, 90, 93, 96, 100, 102, 105, 108, 111, 114, 117, 120, 123, 127, 129, 132, 136, 139, 142, 145, 147, 151, 154, 156, 159, 163, 166, 169, 172, 174, 177, 181

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Positions of strict descents in the Kolakoski sequence A000002. Strict ascents are A156243. - Gus Wiseman, Mar 31 2020

LINKS

Table of n, a(n) for n=1..60.

FORMULA

a(n) = A054353(2n).

A000002(a(n))=2 and A000002(a(n)+1)=1. - Jon Perry, Sep 04 2012

MATHEMATICA

kolagrow[q_]:=If[Length[q]<2, Take[{1, 2}, Length[q]+1], Append[q, Switch[{q[[Length[Split[q]]]], q[[-2]], Last[q]}, {1, 1, 1}, 0, {1, 1, 2}, 1, {1, 2, 1}, 2, {1, 2, 2}, 0, {2, 1, 1}, 2, {2, 1, 2}, 2, {2, 2, 1}, 1, {2, 2, 2}, 1]]]

kol[n_Integer]:=Nest[kolagrow, {1}, n-1];

Join@@Position[Partition[kol[100], 2, 1], {2, 1}] (* Gus Wiseman, Mar 31 2020 *)

CROSSREFS

Cf. A000002, A156243.

The version for prime gaps is A258026.

Sizes of maximal weakly increasing subsequences of A000002 are A332875.

Cf. A054804, A124766, A124769, A225620, A238343, A332273, A333213, A333215, A333256, A333383.

Sequence in context: A039004 A070021 A083354 * A060293 A336803 A220657

Adjacent sequences: A156239 A156240 A156241 * A156243 A156244 A156245

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Feb 07 2009

STATUS

approved