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 A111650 #17 Jun 06 2025 14:47:26
%S A111650 2,4,4,6,6,6,8,8,8,8,10,10,10,10,10,12,12,12,12,12,12,14,14,14,14,14,
%T A111650 14,14,16,16,16,16,16,16,16,16,18,18,18,18,18,18,18,18,18,20,20,20,20,
%U A111650 20,20,20,20,20,20,22,22,22,22,22,22,22,22,22,22,22,24,24,24,24,24,24,24
%N A111650 2n appears n times (n>0).
%C A111650 Seen as a triangle read by rows: T(n,k) = 2*n, 1<=k<=n. - _Reinhard Zumkeller_, Mar 18 2011
%H A111650 Reinhard Zumkeller, <a href="/A111650/b111650.txt">Rows n = 1..128 of triangle, flattened</a>
%F A111650 a(n) = 2*A002024(n). - _Chai Wah Wu_, Jun 06 2025
%t A111650 Table[Table[2n,n],{n,12}]//Flatten (* _Harvey P. Dale_, Apr 21 2018 *)
%o A111650 (Haskell)
%o A111650 a111650 n k = a111650_tabl !! (n-1) !! (k-1)
%o A111650 a111650_row n = a111650_tabl !! (n-1)
%o A111650 a111650_tabl = iterate (\xs@(x:_) -> map (+ 2) (x:xs)) [2]
%o A111650 a111650_list = concat a111650_tabl
%o A111650 -- _Reinhard Zumkeller_, Nov 14 2015, Mar 18 2011
%o A111650 (Python)
%o A111650 from math import isqrt
%o A111650 def A111650(n): return isqrt(n<<3)+1&-2 # _Chai Wah Wu_, Jun 06 2025
%Y A111650 Cf. A000194, A111651, A111652.
%Y A111650 Cf. A001650, A193832, A002024.
%K A111650 easy,nonn,tabl
%O A111650 1,1
%A A111650 _Jonathan Vos Post_, Aug 12 2005