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.

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

Offset

1,2

Comments

First differs from A212121 at a(14). The illustration of initial terms is essentially the same as the illustration of initial terms of A213372, the main entry for this sequence.

Links

Table of n, a(n) for n=1..22.

MIT OpenCourseWare, Energy Levels of Nucleons in a Smoothly-Varying Potential Well

Formula

a(n) = A213372(n)/2.

Example

Written as an irregular triangle in which row n represents the n-th shell of nucleus. Note that row 4 has only one term. Triangle begins:
1;
2, 1;
3, 1, 2;
4;
2, 3, 1, 5;
4, 3, 6, 2, 1;
4, 5, 7, 2, 3, 1;

Crossrefs

Partial sums give A213373. Other version are A004736, A130517, A212121, A213361.

Cf. A213372, A213374.

Sequence in context: A133737 A213361 A212121 * A125047 A323420 A331296

Adjacent sequences: A213368 A213369 A213370 * A213372 A213373 A213374

Keyword

nonn,tabf,hard,more

Author

Omar E. Pol, Jul 16 2012

Status

approved