a(n) = 1/11*(binomial(n,11) - floor(n/11)).

Terms

a(0) =1a(1) =7a(2) =33a(3) =124a(4) =397a(5) =1125a(6) =2893a(7) =6871a(8) =15269a(9) =32065a(10) =64130a(11) =122916a(12) =226922a(13) =405218a(14) =702378a(15) =1185263a(16) =1952198a(17) =3145208a(18) =4966118a(19) =7697483a(20) =11729498a(21) =17594247a(22) =26008887a(23) =37929627a(24) =54618663a(25) =77726559a(26) =109392935a(27) =152368731a(28) =210163767a(29) =287223815