Triangular numbers that are 3-almost primes.

Terms

a(0) =28a(1) =45a(2) =66a(3) =78a(4) =105a(5) =153a(6) =171a(7) =190a(8) =231a(9) =325a(10) =406a(11) =435a(12) =465a(13) =561a(14) =595a(15) =741a(16) =861a(17) =903a(18) =946a(19) =1378a(20) =1653a(21) =2211a(22) =2278a(23) =2485a(24) =3081a(25) =3655a(26) =3741a(27) =4371a(28) =4465a(29) =4753