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 A338120 #22 Jan 30 2021 04:27:33
%S A338120 1,6,20,42,33,156,20,272,342,2058,506,377,930,77,14406,629,162,1640,
%T A338120 559,2162,4624,1166,110,6498,3422,610,342732,4422,506,4970,5256,42,
%U A338120 6162,6806
%N A338120 a(n) is the least index k such that the n-th odd squarefree number A056911(n) divides A110566(k).
%C A338120 According to a theorem proven by Shiu (2016), a(n) exists for all n.
%H A338120 Peter Shiu, <a href="https://arxiv.org/abs/1607.02863">The denominators of harmonic numbers</a>, arXiv:1607.02863 [math.NT], 2016.
%e A338120 n A056911(n) a(n) = k A110566(k)
%e A338120 -- ---------- -------- --------------------------
%e A338120 1 1 1 1 = 1 * 1
%e A338120 2 3 6 3 = 3 * 1
%e A338120 3 5 20 15 = 5 * 3
%e A338120 4 7 42 77 = 7 * 11
%e A338120 5 11 33 11 = 11 * 1
%e A338120 6 13 156 13 = 13 * 1
%e A338120 7 15 20 15 = 15 * 1
%e A338120 8 17 272 17 = 17 * 1
%e A338120 9 19 342 931 = 19 * 49
%e A338120 10 21 2058 1911 = 21 * 91
%e A338120 11 23 506 1725 = 23 * 75
%e A338120 12 29 377 319 = 29 * 11
%e A338120 13 31 930 3751 = 31 * 121
%e A338120 14 33 77 33 = 33 * 1
%e A338120 15 35 14406 2430488445 = 35 * 69442527
%e A338120 16 37 629 20313 = 37 * 549
%e A338120 17 39 162 39 = 39 * 1
%e A338120 18 41 1640 6519 = 41 * 159
%e A338120 19 43 559 645 = 43 * 15
%e A338120 20 47 2162 12831 = 47 * 273
%e A338120 21 51 4624 9537 = 51 * 187
%e A338120 22 53 1166 53 = 53 * 1
%e A338120 23 55 110 55 = 55 * 1
%e A338120 24 57 6498 419498967 = 57 * 7359631
%e A338120 25 59 3422 6431 = 59 * 109
%e A338120 26 61 610 41175 = 61 * 675
%e A338120 27 65 342732 974285 = 65 * 14989
%e A338120 28 67 4422 2211 = 67 * 33
%e A338120 29 69 506 1725 = 69 * 25
%e A338120 30 71 4970 2343 = 71 * 33
%e A338120 31 73 5256 7227 = 73 * 99
%e A338120 32 77 42 77 = 77 * 1
%e A338120 33 79 6162 91801713 = 79 * 1162047
%e A338120 34 83 6806 1200097 = 83 * 14459
%t A338120 max = 64; osf = Select[Range[1, 64, 2], SquareFreeQ]; m = Length[osf]; c = 0; s = Table[0, {m}]; h = 0; lcm = 1; n = 1; While[c < m, h += 1/n; lcm = LCM[lcm, n]; r = lcm/Denominator[h]; Do[If[s[[k]] == 0 && Divisible[r, osf[[k]]], c++; s[[k]] = n], {k, 1, m}]; n++]; s
%Y A338120 Cf. A002805, A003418, A110566, A056911, A112822.
%K A338120 nonn,more
%O A338120 1,2
%A A338120 _Amiram Eldar_, Jan 29 2021