Second differences of A037257.

Terms

a(0) =4a(1) =5a(2) =7a(3) =8a(4) =10a(5) =12a(6) =13a(7) =14a(8) =15a(9) =16a(10) =17a(11) =19a(12) =21a(13) =22a(14) =23a(15) =24a(16) =25a(17) =28a(18) =29a(19) =30a(20) =31a(21) =32a(22) =33a(23) =34a(24) =35a(25) =37a(26) =39a(27) =40a(28) =41a(29) =42