A350455 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.
4, 9, 15, 21, 25, 35, 33, 49, 39, 55, 65, 77, 51, 91, 57, 85, 121, 95, 119, 143, 69, 133, 169, 115, 187, 161, 209, 221, 87, 247, 93, 145, 253, 289, 155, 203, 299, 323, 217, 361, 111, 319, 391, 185, 341, 377, 437, 123, 259, 403, 129, 205, 493, 529, 215, 287, 407
Offset: 2
Examples
Triangle T(n,k) begins:
4;
9;
15;
21, 25;
35 ;
33, 49;
39, 55;
65, 77;
51, 91;
57, 85, 121;
95, 119, 143;
69, 133, 169;
115, 187 ;
161, 209, 221;
87, 247 ;
93, 145, 253, 289;
155, 203, 299, 323;
...
Links
- Alois P. Heinz, Rows n = 2..1000, flattened
- Wikipedia, Goldbach's conjecture
Crossrefs
Programs
-
Maple
T:= n-> seq(`if`(andmap(isprime, [h, 2*n-h]), h*(2*n-h), [][]), h=2..n): seq(T(n), n=2..30);
Comments