Numbers k >= 2 such that for some m >= 2, the sum of the first m k-gonal numbers is again a k-gonal number, excluding the parametric solution m = (k^2-4*k-2)/3 when k==2 (mod 3).
A027696
Numbers k >= 2 such that for some m >= 2, the sum of the first m k-gonal numbers is again a k-gonal number, excluding the parametric solution m = (k^2-4*k-2)/3 when k==2 (mod 3).
Terms
- a(0) =3a(1) =4a(2) =6a(3) =8a(4) =10a(5) =11a(6) =14a(7) =17a(8) =30a(9) =41a(10) =43a(11) =50a(12) =60a(13) =88a(14) =145a(15) =276a(16) =322a(17) =374a(18) =823a(19) =1152
External references
- oeis: A027696