Octahedral torus number: a(n) = n^2 + 2*(Sum_{k=1..n-1} k^2) - 2*(floor((n+1)/2)^2 + 2*(Sum_{k=1..floor((n+1)/2)-1} k^2)) + (1 - (-1)^n)/2.
A050442
Octahedral torus number: a(n) = n^2 + 2*(Sum_{k=1..n-1} k^2) - 2*(floor((n+1)/2)^2 + 2*(Sum_{k=1..floor((n+1)/2)-1} k^2)) + (1 - (-1)^n)/2.
Terms
- a(0) =0a(1) =4a(2) =8a(3) =32a(4) =48a(5) =108a(6) =144a(7) =256a(8) =320a(9) =500a(10) =600a(11) =864a(12) =1008a(13) =1372a(14) =1568a(15) =2048a(16) =2304a(17) =2916a(18) =3240a(19) =4000a(20) =4400a(21) =5324a(22) =5808a(23) =6912a(24) =7488a(25) =8788a(26) =9464a(27) =10976a(28) =11760a(29) =13500
External references
- oeis: A050442