Enneagonal numbers whose sum of digits is also enneagonal.

Terms

a(0) =0a(1) =1a(2) =9a(3) =261a(4) =969a(5) =1350a(6) =6666a(7) =7944a(8) =10071a(9) =13299a(10) =17466a(11) =24486a(12) =33369a(13) =36159a(14) =39804a(15) =42846a(16) =46806a(17) =54375a(18) =57921a(19) =66309a(20) =75264a(21) =80484a(22) =111696a(23) =116754a(24) =128544a(25) =135339a(26) =153825a(27) =167316a(28) =175056a(29) =181374