A213371 - cp's OEIS frontend

A213371 Triangle read by rows in which row n lists the number of pairs of states of the subshells of the n-th shell of the nuclear shell model ordered by energy level in increasing order.

n	a(n)
1	1
2	2
3	1
4	3
5	1
6	2
7	4
8	2
9	3
10	1
11	5
12	4
13	3
14	6
15	2
16	1
17	4
18	5
19	7
20	2
21	3
22	1

[1, 2, 1, 3, 1, 2, 4, 2, 3, 1, 5, 4, 3, 6, 2, 1, 4, 5, 7, 2, 3, 1]