Mass number of the most abundant isotope of the element with atomic number Z = n.

Terms

a(0) =1a(1) =4a(2) =7a(3) =9a(4) =11a(5) =12a(6) =14a(7) =16a(8) =19a(9) =20a(10) =23a(11) =24a(12) =27a(13) =28a(14) =31a(15) =32a(16) =35a(17) =40a(18) =39a(19) =40a(20) =45a(21) =48a(22) =51a(23) =52a(24) =55a(25) =56a(26) =59a(27) =58a(28) =63a(29) =64