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.
k = 2; q = 2^k;
v[t_] := If[t === 0, q - 1, -1];
dd[a_, n_] := With[{m = Floor[(n + 1)/4]},
q^(n - 2) + Switch[Mod[n, 4],
2, 0,
0, -v[a] q^((n - 2)/2) (-1)^(m k),
_, v[a] q^((n - 3)/2) (-1)^(m k)
]];
h[n_, 0, a_] := 1/n Sum[MoebiusMu[d] (dd[a, n/d] - Boole[EvenQ[n]] q^(n/(2d)-1)), {d, Select[Divisors[n], OddQ]}];
Table[h[n, 0, 0], {n, 30}] (* this sequence *)
Table[h[n, 0, 1], {n, 30}] (* A074032 *)
(* Andrey Zabolotskiy, Dec 15 2020 *)
q = 4;
v[t_] := If[t === 0, q - 1, -1];
ddp[a_, n_] := q^(n-2) + q^Quotient[n-2, 2] {v[a], -1, v[1-a], 0}[[Mod[n, 4, 1]]];
h[n_, 1, a_] := 1/n Sum[MoebiusMu[d] ddp[Mod[a+(d-1)/2, 2], n/d], {d, Select[Divisors[n], OddQ]}];
Table[h[n, 1, 0], {n, 30}] (* this sequence *)
Table[h[n, 1, 1], {n, 30}] (* A074034 *)
(* Andrey Zabolotskiy, Dec 17 2020 *)
q = 4;
ddpx[n_] := q^(n-2) + q^Quotient[n-2, 2] {-1, 1, -1, 0}[[Mod[n, 4, 1]]];
h1x[n_] := 1/n Sum[MoebiusMu[d] ddpx[n/d], {d, Select[Divisors[n], OddQ]}];
Table[h1x[n], {n, 30}]
(* Andrey Zabolotskiy, Dec 17 2020 *)
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