OFFSET
1,1
LINKS
Christian Sievers, Table of n, a(n) for n = 1..6
Eric Weisstein's World of Mathematics, Matching
Eric Weisstein's World of Mathematics, Maximum Independent Edge Set
Eric Weisstein's World of Mathematics, Sierpinski Tetrahedron Graph
PROG
(PARI) rd(p)=if(p, pollead(p)*x^poldegree(p), 0);
a(n)={my(s=[1, 0, x, 0, 3*x^2]); for(k=2, n, s=vector(5, i, rd(sum(wx=0, 2, sum(wy=0, 2, sum(wz=0, 2, sum(xy=0, 2, sum(xz=0, 2, sum(yz=0, 2, 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)]))))))))); pollead([1, 4, 6, 4, 1]*s~)} \\ Christian Sievers, Jul 21 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Dec 31 2017
EXTENSIONS
a(4) and beyond from Christian Sievers, Jul 21 2024
STATUS
approved