A210970 Total area of the shadows of the three views of a three-dimensional version of the shell model of partitions with n shells.

0, 3, 9, 18, 34, 55, 91, 136, 208, 301, 439, 616, 876, 1203, 1665, 2256, 3062, 4083, 5459, 7186, 9470, 12335, 16051, 20688, 26648, 34027, 43395, 54966, 69496, 87341, 109591, 136766, 170382, 211293, 261519, 322382, 396694, 486327, 595143, 725954, 883912

Offset

0,2

Comments

For more information see A135010 and A182703.

Links

Table of n, a(n) for n=0..40.

Formula

a(n) = 2*A006128(n) + A000217(n).

Example

For n = 6 the illustration of the three views of a three-dimensional version of the shell model of partitions with 6 shells looks like this:
.
.   A006128(6) = 35     A006128(6) = 35
.
.                 6     6
.               3 3     3 3
.               4 2     4 2
.             2 2 2     2 2 2
.               5 1     5 1
.             3 2 1     3 2 1
.             4 1 1     4 1 1
.           2 2 1 1     2 2 1 1
.           3 1 1 1     3 1 1 1
.         2 1 1 1 1     2 1 1 1 1
.       1 1 1 1 1 1     1 1 1 1 1 1
.
.
.       1 2 5 9 12 6  \
.         1 1 3 5 6    \
.           1 1 2 4     \ 6th slice of
.             1 1 2     / tetrahedron A210961
.               1 1    /
.                 1   /
.
.      A000217(6) = 21
.
The areas of the shadows of the three views are A006128(6) = 35, A006128(6) = 35 and A000217(6) = 21, therefore the total area of the three shadows is 35+35+21 = 91, so a(6) = 91.

Crossrefs

Other versions: A207380, A210979, A210980, A210990, A210991.

Cf. A000217, A006128, A066186, A135010, A138121, A182703, A206437, A210952, A210961.

Sequence in context: A064843 A093446 A256524 * A293406 A295862 A246695

Adjacent sequences: A210967 A210968 A210969 * A210971 A210972 A210973

Keyword

nonn

Author

Omar E. Pol, Apr 22 2012

Status

approved