Number of strings of numbers x(i=1..n) in 0..4 with sum i^3*x(i) equal to n^3*4.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =20a(6) =47a(7) =129a(8) =427a(9) =1196a(10) =3482a(11) =10769a(12) =30174a(13) =86121a(14) =252178a(15) =694285a(16) =1923825a(17) =5380601a(18) =14505330a(19) =39099516a(20) =105522367a(21) =278190141a(22) =731086405a(23) =1916631823a(24) =4945238542a(25) =12702253352a(26) =32495656601a(27) =82177529409a(28) =206786628877