>Terms for 1..56 > >0 0 0 0 0 0 2 2 0 0 2 10 0 0 86 114 0 0 478 860 0 0 5808 10838 0 0 55626 >100426 >0 0 696164 1298600 0 0 7826992 14574366 0 0 100061106 187392994 0 0 >1223587084 2322159814 >0 0 16019866270 30353305134 0 0 207366863690 395899408130 0 0 >2773156759854 5301226883378 This is twice A083527. Tony