Heptagonal numbers for which the digital root is also a heptagonal number.

Terms

a(0) =0a(1) =1a(2) =7a(3) =34a(4) =55a(5) =235a(6) =286a(7) =403a(8) =469a(9) =874a(10) =970a(11) =1177a(12) =1288a(13) =1918a(14) =2059a(15) =2356a(16) =2512a(17) =3367a(18) =3553a(19) =3940a(20) =4141a(21) =5221a(22) =5452a(23) =5929a(24) =6175a(25) =7480a(26) =7756a(27) =8323a(28) =8614a(29) =10144