a(n) = Sum_{d|n} d * binomial(n,d).

Terms

a(0) =1a(1) =4a(2) =6a(3) =20a(4) =10a(5) =102a(6) =14a(7) =352a(8) =270a(9) =1370a(10) =22a(11) =8340a(12) =26a(13) =24234a(14) =16410a(15) =110512a(16) =34a(17) =551754a(18) =38a(19) =1944880a(20) =817992a(21) =7760258a(22) =46a(23) =39190392a(24) =265700a(25) =135208502a(26) =42190254a(27) =570003392a(28) =58a(29) =2631501240