A325301 a(n) is the number of edges of the stepped pyramid with n levels described in A245092.

12, 21, 36, 51, 63, 84, 96, 117, 138, 165, 177, 204, 216, 240, 273, 306, 318, 351, 363

Offset: 1

Author

Omar E. Pol, Apr 16 2019

Keywords

• nonn
• more

Comments

To calculate a(n) consider that levels greater than n do not exist.

Examples

			For n = 1 the first level of the stepped pyramid (starting from the top) is a cube, and a cube has 12 edges, so a(1) = 12.
		

Links

• Omar E. Pol, Perspective view of the pyramid (first 16 levels)

Crossrefs

Cf. A325300 (number of faces), A325302 (number of vertices).

Cf. A196020, A235791, A236104, A237270, A237271, A237591, A237593, A245092, A262626, A294848, A294849, A317109, A323648.

Formula

a(n) = A325300(n) + A325302(n) - 2 (Euler's formula).