Number of 4-cycles in the n-Sierpinski tetrahedron graph.

Terms

a(0) =3a(1) =39a(2) =156a(3) =624a(4) =2496a(5) =9984a(6) =39936a(7) =159744a(8) =638976a(9) =2555904a(10) =10223616a(11) =40894464a(12) =163577856a(13) =654311424a(14) =2617245696a(15) =10468982784a(16) =41875931136a(17) =167503724544a(18) =670014898176