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 A197871 #17 Aug 16 2022 16:05:30
%S A197871 0,2,1,4,3,1,6,6,2,1,9,9,4,2,11,13,7,3,1,15,17,10,4,2,18,22,13,7,2,1,
%T A197871 22,26,19,8,4,1,25,34,22,12,4,2,30,40,28,13,7,2,34,48,32,18,7,3,1,39,
%U A197871 56,38,21,9,4,1,44,62,48,24,11,4,2,48,75,51,29,13,6,2
%N A197871 Irregular triangle T(n,k) of the number of numbers with k prime factors (repetitions allowed) less than n^2.
%D A197871 G. J. O. Jameson, The Prime Number Theorem, Cambridge, 2004, p.145.
%e A197871 In the third row, reading from the left, 6 is the number of primes <= 16, 6 is the number of semiprimes <= 16, 2 is the number of numbers with three prime divisors (repetitions allowed) <= 16, and 1 is the number of numbers with four divisors <= 16.
%e A197871 The triangle begins:
%e A197871 0
%e A197871 2 1
%e A197871 4 3 1
%e A197871 6 6 2 1
%e A197871 9 9 4 2
%e A197871 11 13 7 3 1
%e A197871 15 17 10 4 2
%e A197871 ...
%t A197871 Join[{0}, Flatten[Table[Transpose[Tally[Table[Plus @@ Last /@ FactorInteger[i], {i, 2, n^2}]]][[2]], {n, 2, 15}]]]
%o A197871 (PARI) T(n,k) = #select(x->(bigomega(x) == k), [1..n^2]);
%o A197871 row(n) = my(v = vector(n, k, T(n,k))); my(pos); for (k=1, n, if (v[k], pos=k)); Vec(v, pos); \\ _Michel Marcus_, Aug 16 2022
%Y A197871 Similar to A052130.
%K A197871 nonn,tabf
%O A197871 1,2
%A A197871 _Daniel Tisdale_, Oct 18 2011