Second differences of Bell numbers.

Terms

a(0) =1a(1) =2a(2) =7a(3) =27a(4) =114a(5) =523a(6) =2589a(7) =13744a(8) =77821a(9) =467767a(10) =2972432a(11) =19895813a(12) =139824045a(13) =1028804338a(14) =7905124379a(15) =63287544055a(16) =526827208698