Truncated centered square numbers: a(n) = 14*n^2 - 22*n + 9.

Terms

a(0) =1a(1) =21a(2) =69a(3) =145a(4) =249a(5) =381a(6) =541a(7) =729a(8) =945a(9) =1189a(10) =1461a(11) =1761a(12) =2089a(13) =2445a(14) =2829a(15) =3241a(16) =3681a(17) =4149a(18) =4645a(19) =5169a(20) =5721a(21) =6301a(22) =6909a(23) =7545a(24) =8209a(25) =8901a(26) =9621a(27) =10369a(28) =11145a(29) =11949