Pentagonal numbers with only odd digits.

Terms

a(0) =1a(1) =5a(2) =35a(3) =51a(4) =117a(5) =715a(6) =1335a(7) =1717a(8) =3151a(9) =3577a(10) =5551a(11) =5735a(12) =7315a(13) =7957a(14) =15555a(15) =55777a(16) =71177a(17) =73151a(18) =99717a(19) =135751a(20) =171197a(21) =319935a(22) =331115a(23) =335357a(24) =371757a(25) =377755a(26) =711737a(27) =755795a(28) =935755a(29) =1111551