Octagonal numbers of the form C*(3C - 2) with 3C - 2 = k^2 and C a composite number.

Terms

a(0) =96a(1) =225a(2) =1408a(3) =3400a(4) =9633a(5) =12936a(6) =22016a(7) =43681a(8) =53600a(9) =78408a(10) =93633a(11) =130625a(12) =152776a(13) =205408a(14) =308481a(15) =350208a(16) =446216a(17) =696008a(18) =854400a(19) =943041a(20) =1250656a(21) =1493896a(22) =1628033a(23) =1923201a(24) =2085000a(25) =2439008a(26) =3280256a(27) =3774408a(28) =4041441