Number of strings of numbers x(i=1..n) in 0..2 with sum i*x(i)^2 equal to n*4.

Terms

a(0) =1a(1) =1a(2) =3a(3) =5a(4) =8a(5) =17a(6) =31a(7) =63a(8) =129a(9) =244a(10) =458a(11) =860a(12) =1544a(13) =2721a(14) =4734a(15) =8044a(16) =13423a(17) =22097a(18) =35750a(19) =57052a(20) =89944a(21) =139918a(22) =215240a(23) =327754a(24) =493888a(25) =737327a(26) =1091368a(27) =1601767a(28) =2332587a(29) =3372198