40-gonal numbers: a(n) = 38*n*(n-1)/2 + n.

Terms

a(0) =0a(1) =1a(2) =40a(3) =117a(4) =232a(5) =385a(6) =576a(7) =805a(8) =1072a(9) =1377a(10) =1720a(11) =2101a(12) =2520a(13) =2977a(14) =3472a(15) =4005a(16) =4576a(17) =5185a(18) =5832a(19) =6517a(20) =7240a(21) =8001a(22) =8800a(23) =9637a(24) =10512a(25) =11425a(26) =12376a(27) =13365a(28) =14392a(29) =15457