a(n) is the smallest prime factor in A030426(n).

Terms

a(0) =2a(1) =5a(2) =13a(3) =89a(4) =233a(5) =1597a(6) =37a(7) =28657a(8) =514229a(9) =557a(10) =73a(11) =2789a(12) =433494437a(13) =2971215073a(14) =953a(15) =353a(16) =4513a(17) =269a(18) =6673a(19) =9375829a(20) =157a(22) =1069a(23) =193a(24) =743519377a(25) =519121a(26) =1247833a(27) =827728777a(28) =677a(29) =27941a(32) =277