A212123 - OEIS

A212123

Total number of pairs of states of the first n subshells of the nuclear shell model in which the subshells are ordered by energy level in increasing order.

1, 3, 4, 7, 8, 10, 14, 16, 19, 20, 25, 29, 32, 34, 35, 41, 46, 50, 53, 55, 56, 63, 68, 71, 77, 81, 82, 84, 92

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OFFSET

1,2

COMMENTS

First differs from A213363 at a(12).

LINKS

Table of n, a(n) for n=1..29.

FORMULA

a(n) = A212124(n)/2.

EXAMPLE

Example 1: written as a triangle in which row i is related to the (i-1)st level of nucleus. Triangle begins:

3, 4;

7, 8, 10;

14, 16, 19, 20;

25, 29, 32, 34, 35;

41, 46, 50, 53, 55, 56;

63, 68, 71, 77, 81, 82, 84;

...

Example 2: written as an irregular triangle in which row j is related to the j-th shell of nucleus. Note that in this case row 4 has only one term. Triangle begins:

3, 4;

7, 8, 10;

14,

16, 19, 20, 25;

29, 32, 34, 35, 41;

46, 50, 53, 55, 56, 63;

68, 71, 77, 81, 82, 84, 92;

...

CROSSREFS

Partial sums of A212121. Other versions are A210983, A212013, A213363, A213373.

Cf. A000292, A004006, A212122, A212124.

Sequence in context: A338733 A210983 A213363 * A213373 A363353 A332059

Adjacent sequences: A212120 A212121 A212122 * A212124 A212125 A212126

KEYWORD

nonn,tabf,hard,more

AUTHOR

Omar E. Pol, Jun 03 2012

STATUS

approved