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 A055223 #13 Aug 11 2025 01:54:41
%S A055223 1,1,1,1,2,1,1,2,3,3,3,3,2,3,4,5,5,5,4,3,5,6,7,5,8,8,6,8,10,10,8,6,7,
%T A055223 8,8,10,7,9,9,10,11,10,9,10,9,11,11,11,11,12,13,13,12,14,10,14,17,15,
%U A055223 13,13,12,15,14,16,15,12,14,15,15,16,15,15,15,16,13,12,16,17,14,20,20,20
%N A055223 One-fourth the digital sum of base 5 representations of 2^n.
%e A055223 a(19) = 4 because 2^20 = 1048576 = 232023301 (to scale 5) and (2+3+2+0+2+3+3+0+1)/4 = 4.
%t A055223 a[n_] := 1/4* Module[{aux = IntegerDigits[2^n, 5]},Sum[aux[[i]], {i, 1, Length[aux]}]]; Table[a[n], {n, 2, 83}] (* _José María Grau Ribas_, Feb 13 2010 *)
%Y A055223 Cf. A000866.
%K A055223 nonn,base
%O A055223 2,5
%A A055223 _Lekraj Beedassy_, Jun 20 2000
%E A055223 More terms from _James Sellers_, Jul 04 2000