4th differences of Bell numbers.

Terms

a(0) =4a(1) =15a(2) =67a(3) =322a(4) =1657a(5) =9089a(6) =52922a(7) =325869a(8) =2114719a(9) =14418716a(10) =103004851a(11) =769052061a(12) =5987339748a(13) =48506099635a(14) =408157244967