OFFSET
1,2
REFERENCES
G. J. O. Jameson, The Prime Number Theorem, Cambridge, 2004, p.145.
EXAMPLE
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.
The triangle begins:
0
2 1
4 3 1
6 6 2 1
9 9 4 2
11 13 7 3 1
15 17 10 4 2
...
MATHEMATICA
Join[{0}, Flatten[Table[Transpose[Tally[Table[Plus @@ Last /@ FactorInteger[i], {i, 2, n^2}]]][[2]], {n, 2, 15}]]]
PROG
(PARI) T(n, k) = #select(x->(bigomega(x) == k), [1..n^2]);
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
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Daniel Tisdale, Oct 18 2011
STATUS
approved