A325301 - OEIS

%I #14 Dec 31 2020 11:11:15

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

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

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

%H Omar E. Pol, <a href="http://www.polprimos.com/imagenespub/polpyr05.jpg">Perspective view of the pyramid (first 16 levels)</a>

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

%e 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.

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

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

%K nonn,more

%O 1,1

%A _Omar E. Pol_, Apr 16 2019