Odd octagonal pyramidal numbers.

Terms

a(0) =1a(1) =9a(2) =135a(3) =231a(4) =765a(5) =1045a(6) =2275a(7) =2835a(8) =5049a(9) =5985a(10) =9471a(11) =10879a(12) =15925a(13) =17901a(14) =24795a(15) =27435a(16) =36465a(17) =39865a(18) =51319a(19) =55575a(20) =69741a(21) =74949a(22) =92115a(23) =98371a(24) =118825a(25) =126225a(26) =150255a(27) =158895a(28) =186789a(29) =196765