Successively larger gaps in Ulam numbers start at this Ulam number.

Terms

a(0) =1a(1) =4a(2) =8a(3) =18a(4) =38a(5) =87a(6) =114a(7) =155a(8) =282a(9) =751a(10) =949a(11) =1257a(12) =1553a(13) =1858a(14) =2178a(15) =4800a(16) =5384a(17) =18796a(18) =37562a(19) =64420a(20) =252719a(21) =933709a(22) =289738117a(23) =332250401a(24) =667752899a(25) =699497052a(26) =966290117a(27) =224582902442a(28) =319654121875a(29) =418843012121