Omit first term from A160539 and divide by 7.

Terms

a(0) =0a(1) =1a(2) =5a(3) =20a(4) =70a(5) =221a(6) =646a(7) =1772a(8) =4614a(9) =11490a(10) =27537a(11) =63808a(12) =143514a(13) =314279a(14) =671872a(15) =1405260a(16) =2881030a(17) =5799093a(18) =11476452a(19) =22357584a(20) =42922558a(21) =81284699a(22) =151974124a(23) =280739800a(24) =512761178a(25) =926568075a(26) =1657448779a(27) =2936506316a(28) =5155349836a(29) =8972488674