%I #25 Jan 04 2022 18:29:11
%S 4,9,15,21,25,35,33,49,39,55,65,77,51,91,57,85,121,95,119,143,69,133,
%T 169,115,187,161,209,221,87,247,93,145,253,289,155,203,299,323,217,
%U 361,111,319,391,185,341,377,437,123,259,403,129,205,493,529,215,287,407
%N T(n,k) is the k-th semiprime whose sum of prime factors equals 2n, triangle T(n,k), n>=2, 1<=k<=A045917(n), read by rows.
%C Assuming Goldbach's conjecture, no row is empty.
%H Alois P. Heinz, <a href="/A350455/b350455.txt">Rows n = 2..1000, flattened</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Goldbach%27s_conjecture">Goldbach's conjecture</a>
%e Triangle T(n,k) begins:
%e 4;
%e 9;
%e 15;
%e 21, 25;
%e 35 ;
%e 33, 49;
%e 39, 55;
%e 65, 77;
%e 51, 91;
%e 57, 85, 121;
%e 95, 119, 143;
%e 69, 133, 169;
%e 115, 187 ;
%e 161, 209, 221;
%e 87, 247 ;
%e 93, 145, 253, 289;
%e 155, 203, 299, 323;
%e ...
%p T:= n-> seq(`if`(andmap(isprime, [h, 2*n-h]), h*(2*n-h), [][]), h=2..n):
%p seq(T(n), n=2..30);
%Y Column k=1 gives A073046.
%Y Last elements of rows give A102084.
%Y Row sums give A228553.
%Y Row products give A337568.
%Y Row lengths give A045917.
%Y Cf. A000040, A001358, A046315, A350419.
%K nonn,look,tabf
%O 2,1
%A _Alois P. Heinz_, Dec 31 2021