Heptagonal numbers for which the sum of the digits is also a heptagonal number.

Terms

a(0) =0a(1) =1a(2) =7a(3) =34a(4) =189a(5) =403a(6) =783a(7) =1782a(8) =2673a(9) =3186a(10) =3744a(11) =4347a(12) =6426a(13) =7209a(14) =8037a(15) =8910a(16) =10791a(17) =11122a(18) =12852a(19) =13950a(20) =15093a(21) =16281a(22) =17514a(23) =21022a(24) =21483a(25) =24354a(26) =27405a(27) =30636a(28) =32319a(29) =34047