Number of different closest packings of equal spheres for rhombohedral crystals having repeat period n.

A371992

Number of different closest packings of equal spheres for rhombohedral crystals having repeat period n.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =1a(4) =2a(5) =3a(6) =5a(7) =8a(8) =15a(9) =23a(10) =41a(11) =70a(12) =126a(13) =223a(14) =406a(15) =740a(16) =1370a(17) =2545a(18) =4769a(19) =8977a(20) =16985a(21) =32261a(22) =61469a(23) =117488a(24) =225060a(25) =432159a(26) =831235a(27) =1601796a(28) =3090926a(29) =5973198

External references