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 A140282 #16 Feb 01 2019 19:59:06
%S A140282 0,4,8,9,13,17,18,22,26,27,31,35,36,40,44,45,49,53,54,58,62,63,67,71,
%T A140282 72,76,80,81,85,89,90,94,98,99,103,107,108,112,116,117,121,125,126,
%U A140282 130,134,135,139,143,144,148,152,153,157,161,162,166,170,171,175,179,180,184
%N A140282 Numbers k such that A000330(k) is multiple of 3.
%C A140282 k mod 3 is periodic: 0,1,2, 0,1,2, 0,1,2, 0,1,2, 0,1,2, 0,1,2.
%H A140282 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1).
%F A140282 k*(1 + k)*(1 + 2*k) is multiple of 18; a(0..2)=0,4,8; a(n) = a(n-3) + 9 for n > 2.
%F A140282 a(n) = 3*(n-floor(n/3)) + n. - _Gary Detlefs_, Mar 27 2010
%F A140282 a(n) = 3*n + A010872(n). - _Wesley Ivan Hurt_, Jul 07 2013
%F A140282 G.f.: x*(x+2)^2 / ( (1+x+x^2)*(x-1)^2 ). - _R. J. Mathar_, Jul 13 2013
%p A140282 seq(3*(n-floor(n/3)) +n, n= 0..61); # _Gary Detlefs_, Mar 27 2010
%t A140282 s={};Do[If[Mod[m*(1+m)*(1+2*m),18]==0,s={s,m}],{m,0,400}];Flatten[s]
%t A140282 Flatten[Position[Accumulate[Range[0,200]^2],_?(Mod[#,3]==0&)]]-1 (* or *) LinearRecurrence[{1,0,1,-1},{0,4,8,9},100] (* _Harvey P. Dale_, Mar 08 2018 *)
%Y A140282 Cf. A000330.
%K A140282 nonn,easy
%O A140282 0,2
%A A140282 _Zak Seidov_, May 23 2008