This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A156242 #19 Apr 02 2020 07:51:56
%S A156242 3,6,9,12,15,19,21,24,27,30,33,36,39,42,45,47,50,54,57,60,63,66,69,72,
%T A156242 75,77,81,84,87,90,93,96,100,102,105,108,111,114,117,120,123,127,129,
%U A156242 132,136,139,142,145,147,151,154,156,159,163,166,169,172,174,177,181
%N A156242 Bisection of A054353.
%C A156242 Positions of strict descents in the Kolakoski sequence A000002. Strict ascents are A156243. - _Gus Wiseman_, Mar 31 2020
%F A156242 a(n) = A054353(2n).
%F A156242 A000002(a(n))=2 and A000002(a(n)+1)=1. - _Jon Perry_, Sep 04 2012
%t A156242 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]]]
%t A156242 kol[n_Integer]:=Nest[kolagrow,{1},n-1];
%t A156242 Join@@Position[Partition[kol[100],2,1],{2,1}] (* _Gus Wiseman_, Mar 31 2020 *)
%Y A156242 Cf. A000002, A156243.
%Y A156242 The version for prime gaps is A258026.
%Y A156242 Sizes of maximal weakly increasing subsequences of A000002 are A332875.
%Y A156242 Cf. A054804, A124766, A124769, A225620, A238343, A332273, A333213, A333215, A333256, A333383.
%K A156242 nonn
%O A156242 1,1
%A A156242 _Benoit Cloitre_, Feb 07 2009