OFFSET
1,2
COMMENTS
First differs from A213363 at a(12).
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:
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;
...
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:
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;
...
CROSSREFS
KEYWORD
nonn,tabf,hard,more
AUTHOR
Omar E. Pol, Jun 03 2012
STATUS
approved