a(n) = A100092(n^2+n+1).

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =28a(5) =65a(6) =147a(7) =321a(8) =678a(9) =1382a(10) =2738a(11) =5289a(12) =9985a(13) =18452a(14) =33455a(15) =59616a(16) =104556a(17) =180690a(18) =308058a(19) =518648a(20) =863037a(21) =1420480a(22) =2314170a(23) =3734063a(24) =5970888a(25) =9466452a(26) =14887746a(27) =23235296a(28) =36000876a(29) =55395893