Triangle of truncated triangular numbers: k-th term in n-th row is number of dots in hexagon of sides k, n-k, k, n-k, k, n-k.
A008867
Triangle of truncated triangular numbers: k-th term in n-th row is number of dots in hexagon of sides k, n-k, k, n-k, k, n-k.
Terms
- a(0) =1a(1) =3a(2) =3a(3) =6a(4) =7a(5) =6a(6) =10a(7) =12a(8) =12a(9) =10a(10) =15a(11) =18a(12) =19a(13) =18a(14) =15a(15) =21a(16) =25a(17) =27a(18) =27a(19) =25a(20) =21a(21) =28a(22) =33a(23) =36a(24) =37a(25) =36a(26) =33a(27) =28a(28) =36a(29) =42
External references
- oeis: A008867