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 A277601 #4 Dec 03 2016 11:52:09
%S A277601 4,9,14,19,24,29,34,39,40,44,49,54,59,64,69,74,79,84,89,90,94,99,104,
%T A277601 109,114,119,124,129,134,139,140,144,149,154,159,164,169,174,179,184,
%U A277601 189,190,194,199,204,209,214,219,224,229,234,239,240,244,249,254
%N A277601 (1/2)*A277595.
%H A277601 Clark Kimberling, <a href="/A277601/b277601.txt">Table of n, a(n) for n = 1..10000</a>
%t A277601 z = 260; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
%t A277601 p[b_, d_] := Flatten[Position[a[b], d]]
%t A277601 p[10, 2]/2 (* A277597 *)
%t A277601 p[10,4]/3 (* A277598 *)
%t A277601 p[10,5]/5 (* A277599 *)
%t A277601 p[10,6]/2 (* A277600 *)
%t A277601 p[10,8]/2 (* A277601 *)
%Y A277601 Cf. A277593, A277597-A277600.
%K A277601 nonn,easy
%O A277601 1,1
%A A277601 _Clark Kimberling_, Nov 12 2016