Triangular numbers t which are average of two consecutive primes p and p+4.

Terms

a(0) =15a(1) =21a(2) =45a(3) =105a(4) =231a(5) =351a(6) =465a(7) =741a(8) =861a(9) =1431a(10) =1485a(11) =3081a(12) =3321a(13) =4005a(14) =7875a(15) =10731a(16) =11175a(17) =11781a(18) =13695a(19) =14535a(20) =17205a(21) =17391a(22) =18915a(23) =21321a(24) =22155a(25) =23871a(26) =30135a(27) =33411a(28) =36585a(29) =39621