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 A372902 #7 May 17 2024 01:45:19
%S A372902 1,2,6,33,42,154,198,258,270,342,850,1170,1666,1806,2295,2574,3262,
%T A372902 3366,3834,4070,4654,4970,5439,6006,6118,6162,6699,7095,7254,7497,
%U A372902 7595,10241,11475,12642,14014,15345,17470,17670,18018,19845,22446,23994,24570,24651,25245,25974,26334
%N A372902 Numbers k that divide the k-th large Schröder number.
%C A372902 Numbers k such that k | A006318(k).
%H A372902 Amiram Eldar, <a href="/A372902/b372902.txt">Table of n, a(n) for n = 1..434</a>
%e A372902 2 is a term since A001850(2) = 6 = 2 * 3 is divisible by 2.
%e A372902 6 is a term since A001850(6) = 1806 = 6 * 301 is divisible by 6.
%t A372902 seq[kmax_] := Module[{sc0 = 1, sc1 = 2, sc2, s = {1}}, Do[sc2 = ((6*k-3)*sc1 - (k-2)*sc0)/(k+1); If[Divisible[sc2, k], AppendTo[s, k]]; sc0 = sc1; sc1 = sc2, {k, 2, kmax}]; s]; seq[27000]
%o A372902 (PARI) lista(kmax) = {my(sc0 = 1, sc1 = 2, sc2); print1(1, ", "); for(k = 2, kmax, sc2 = ((6*k-3)*sc1 - (k-2)*sc0)/(k+1); if(!(sc2 % k), print1(k, ", ")); sc0 = sc1; sc1 = sc2);}
%Y A372902 Cf. A006318.
%Y A372902 Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).
%K A372902 nonn
%O A372902 1,2
%A A372902 _Amiram Eldar_, May 16 2024