Partial sums of A002055.

Terms

a(0) =1a(1) =10a(2) =66a(3) =366a(4) =1851a(5) =8858a(6) =40890a(7) =184098a(8) =813948a(9) =3549758a(10) =15317294a(11) =65537334a(12) =278489619a(13) =1176688494a(14) =4948173294a(15) =20723897214a(16) =86494746204a(17) =359915608314