OFFSET
0,2
COMMENTS
a(3) has 264 digits and a(4) has 574 digits.
The Megaminx is a dodecahedron-shaped puzzle similar to the Rubik's Cube. The rotational axes of the pieces are perpendicular to the faces. Here only a Megaminx of odd size is considered, see the picture below showing the relationship between the Megaminx of size 2n and 2n+1.
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..4
Michael Gottlieb's blogger, Notes on Twisty Puzzles
Jianing Song, Relationship between the Megaminx of size 2n and 2n+1
Wikipedia, Megaminx
FORMULA
a(0) = 1; a(n) = 30! * 20! * 60!^(n^2-1) * 5!^(-12*n^2+12*n) * 2^(28-n) * 3^19 for n > 0.
EXAMPLE
See the Michael Gottlieb link above.
PROG
(PARI) a(n) = if(n, 30! * 20! * 60!^(n^2-1) * 5!^(-12*n^2+12*n) * 2^(28-n) * 3^19, 1)
CROSSREFS
KEYWORD
nonn,bref
AUTHOR
Jianing Song, Jul 13 2019
STATUS
approved