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 A331820 #8 Jan 28 2020 03:57:12
%S A331820 1,2,3,8,14,15,20,32,35,56,62,63,68,80,90,95,124,125,128,174,184,185,
%T A331820 215,224,244,245,248,254,255,260,272,275,300,304,305,320,335,342,468,
%U A331820 469,484,485,512,515,544,545,552,575,594,636,720,762,784,785,804,846,896
%N A331820 Positive numbers k such that k and k + 1 are both negabinary-Niven numbers (A331728).
%H A331820 Amiram Eldar, <a href="/A331820/b331820.txt">Table of n, a(n) for n = 1..10000</a>
%e A331820 8 is a term since both 8 and 8 + 1 = 9 are negabinary-Niven numbers: A039724(8) = 11000 and 1 + 1 + 0 + 0 + 0 = 2 is a divisor of 8, and A039724(9) = 11001 and 1 + 1 + 0 + 0 + 1 = 3 is a divisor of 9.
%t A331820 negaBinWt[n_] := negaBinWt[n] = If[n == 0, 0, negaBinWt[Quotient[n - 1, -2]] + Mod[n, 2]]; negaBinNivenQ[n_] := Divisible[n, negaBinWt[n]]; c = 0; k = 1; s = {}; v = Table[-1, {2}]; While[c < 60, If[negaBinNivenQ[k], v = Join[Rest[v], {k}]; If[AllTrue[Differences[v], # == 1 &], c++; AppendTo[s, k - 1]]]; k++]; s
%Y A331820 Cf. A027615, A039724, A328209, A328213, A330927, A330931, A331086, A331089, A331728.
%K A331820 nonn,base
%O A331820 1,2
%A A331820 _Amiram Eldar_, Jan 27 2020