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

A371991

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

Terms

    a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =2a(6) =3a(7) =6a(8) =6a(9) =16a(10) =21a(11) =42a(12) =63a(13) =129a(14) =201a(15) =404a(16) =685a(17) =1340a(18) =2385a(19) =4625a(20) =8487a(21) =16409a(22) =30735a(23) =59282a(24) =112530a(25) =217182a(26) =415605a(27) =803076a(28) =1545463a(29) =2990945

External references