Even 10-gonal (or decagonal) numbers.

Terms

a(0) =0a(1) =10a(2) =52a(3) =126a(4) =232a(5) =370a(6) =540a(7) =742a(8) =976a(9) =1242a(10) =1540a(11) =1870a(12) =2232a(13) =2626a(14) =3052a(15) =3510a(16) =4000a(17) =4522a(18) =5076a(19) =5662a(20) =6280a(21) =6930a(22) =7612a(23) =8326a(24) =9072a(25) =9850a(26) =10660a(27) =11502a(28) =12376a(29) =13282