Triangular numbers with only odd digits.

Terms

a(0) =1a(1) =3a(2) =15a(3) =55a(4) =91a(5) =153a(6) =171a(7) =351a(8) =595a(9) =1711a(10) =1953a(11) =5151a(12) =5995a(13) =9591a(14) =11175a(15) =11935a(16) =15753a(17) =15931a(18) =17391a(19) =17955a(20) =31375a(21) =33153a(22) =35511a(23) =73153a(24) =153735a(25) =171991a(26) =173755a(27) =193131a(28) =193753a(29) =371953