OFFSET
1,1
LINKS
Christian Sievers, Table of n, a(n) for n = 1..5
Eric Weisstein's World of Mathematics, Edge Cover
Eric Weisstein's World of Mathematics, Sierpinski Tetrahedron Graph
PROG
(PARI) a(n)={my(s=[1, 0, 1, 4, 41]); for(k=2, n, s=vector(5, i, sum(wx=1, 3, sum(wy=1, 3, sum(wz=1, 3, sum(xy=1, 3, sum(xz=1, 3, sum(yz=1, 3, s[1+(i>1)+(wx%2)+(wy%2)+(wz%2)]*s[1+(i>2)+(wx\2)+(xy%2)+(xz%2)]*s[1+(i>3)+(wy\2)+(xy\2)+(yz%2)]*s[1+(i>4)+(wz\2)+(xz\2)+(yz\2)])))))))); s[5]} \\ Christian Sievers, Jul 20 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Dec 27 2017
EXTENSIONS
a(3) and beyond from Christian Sievers, Jul 20 2024
STATUS
approved