Write numbers from 1 to n(n+1)/2 in a left-justified lower triangular array (a) downwards and (b) across; a(n) is number of numbers in same position in both.
A028949
Write numbers from 1 to n(n+1)/2 in a left-justified lower triangular array (a) downwards and (b) across; a(n) is number of numbers in same position in both.
Terms
- a(0) =1a(1) =3a(2) =4a(3) =4a(4) =5a(5) =4a(6) =4a(7) =6a(8) =4a(9) =6a(10) =4a(11) =6a(12) =6a(13) =4a(14) =6a(15) =4a(16) =6a(17) =6a(18) =4a(19) =6a(20) =4a(21) =5a(22) =8a(23) =4a(24) =10a(25) =4a(26) =4a(27) =6a(28) =6a(29) =10
External references
- oeis: A028949