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 A353385 #10 Apr 21 2022 09:15:51
%S A353385 1,2,3,4,5,6,10,12,15,20,30,8,9,16,18,24,25,36,40,45,48,50,72,75,80,
%T A353385 90,100,144,150,200,225,400,450,27,32,54,64,96,108,125,135,160,192,
%U A353385 216,250,270,288,320,375,432,500,576,675,750,800,864,1000,1125,1350,1600
%N A353385 Irregular triangle T(n,k) with row n listing A051037(j) not divisible by 60 such that A352219(j) = n.
%C A353385 All terms in A051037 are products T(n,k)*60^j, j >= 0.
%C A353385 When expressed in base 60, T(n,k) does not end in zero, yet 1/T(n,k) is a terminating fraction, regular to 60.
%C A353385 The first 11 terms are the proper divisors of 60.
%C A353385 For these reasons, the terms may be called sexagesimal "proper regular" numbers.
%D A353385 G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, Chapter IX: The Representation of Numbers by Decimals, Theorem 136. 8th ed., Oxford Univ. Press, 2008, 144-145.
%H A353385 Michael De Vlieger, <a href="/A353385/b353385.txt">Table of n, a(n) for n = 0..10250</a> (rows n = 1..40, flattened)
%H A353385 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Sexagesimal.html">Sexagesimal</a>
%H A353385 Wikipedia, <a href="http://en.wikipedia.org/wiki/Regular_number">Regular number</a>.
%F A353385 Row 0 contains the empty product, thus row length = 1.
%F A353385 For n > 0, length of row n = 12(n-1) + 10 = A017641(n-1).
%e A353385 For row w, plot terms m = 2^x * 3^y * 5^z at (x,y,z). Rows are labeled below the figures parenthetically for clarity. The x axis points toward the bottom right, the y axis to the bottom left, and the z axis upward. In the plot, we mark terms from previous rows by ".", and use "*" to show the origin, that is, the empty product 1:
%e A353385 125
%e A353385 375 250
%e A353385 1125 750 500
%e A353385 3375 2250 1000
%e A353385 6750 2000
%e A353385 25 . 4000
%e A353385 75 50 . . 8000
%e A353385 225 150 100 . . .
%e A353385 450 200 675 . .
%e A353385 400 1350 .
%e A353385 5 . . 800
%e A353385 15 10 . . . . 1600
%e A353385 30 20 45 . . . . .
%e A353385 90 40 135 . .
%e A353385 80 270 .
%e A353385 1 * * * 160
%e A353385 3 2 . . . . 320
%e A353385 6 4 9 . . . . .
%e A353385 12 18 . 8 27 . . .
%e A353385 36 24 16 54 . . .
%e A353385 72 48 108 . . 32
%e A353385 144 216 . 96 64
%e A353385 432 288 192
%e A353385 864 432
%e A353385 1728
%e A353385 (0) (1) (2) (3)
%e A353385 The terms in row w are sorted, hence row 1 has {2, 3, 4, 5, 6, 10, 12, 15, 20, 30}.
%t A353385 Block[{t, s = DeleteCases[Sort[Flatten[Table[{2^a* 3^b * 5^c, Max[Ceiling[a/2], b, c]}, {a, 0, Log2[#]}, {b, 0, Log[3, #/(2^a)]}, {c, 0, Log[5, #/(2^a*3^b)]}], 2]] &[60^3], _?(Mod[First[#], 60] == 0 &)]}, #[[1 ;; 2 + LengthWhile[Rest@ Differences[Length /@ #], # == 12 &]]] &@ Map[s[[#, 1]] &, Values@ PositionIndex[s[[All, -1]]]]] // Flatten
%Y A353385 Cf. A017641, A051037, A352219.
%K A353385 nonn,easy,base,tabf
%O A353385 0,2
%A A353385 _Michael De Vlieger_, Apr 15 2022