|
| |
|
|
A115099
|
|
a(0)=4, a(n)=3*a(n-1)-4.
|
|
8
| |
|
|
4, 8, 20, 56, 164, 488, 1460, 4376, 13124, 39368, 118100, 354296, 1062884, 3188648, 9565940, 28697816, 86093444, 258280328, 774840980, 2324522936, 6973568804, 20920706408, 62762119220, 188286357656, 564859072964, 1694577218888
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,1
|
|
|
COMMENTS
| A tetrahedron has 4 faces. Let's cut every corner so that we get triangular faces. This polyhedron has 8 faces. This procedure gives 4,8,20,56... faced polyhedra.
|
|
|
LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..300
|
|
|
FORMULA
| a(n)=2*3^n+2
|
|
|
EXAMPLE
| a(4)=164=2*3^4+2=2*81+2=3*a(3)-4=3*56-4
|
|
|
MAPLE
| seq(2*3^i+2, i=0..30);
|
|
|
MATHEMATICA
| a=4; lst={a}; Do[a=a*3-4; AppendTo[lst, a], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 25 2008]
|
|
|
PROG
| (MAGMA) [2*3^n+2: n in [0..30]]; // Vincenzo Librandi, Jun 05 2011
|
|
|
CROSSREFS
| Cf. A003462, A007051, A034472, A024023, A067771, A029858, A134931 [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 25 2008]
Sequence in context: A009916 A203167 A123861 * A060919 A009333 A187010
Adjacent sequences: A115096 A115097 A115098 * A115100 A115101 A115102
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Miklos Kristof (kristmikl(AT)freemail.hu), Mar 02 2006
|
| |
|
|
