Expansion of g.f.: (1-4*z-sqrt(1-8*z+12*z^2+8*z^3-4*z^4))/(2*z^2(1-z)).
A256939
Expansion of g.f.: (1-4*z-sqrt(1-8*z+12*z^2+8*z^3-4*z^4))/(2*z^2(1-z)).
Terms
- a(0) =1a(1) =3a(2) =13a(3) =57a(4) =257a(5) =1185a(6) =5573a(7) =26661a(8) =129437a(9) =636429a(10) =3163725a(11) =15877101a(12) =80340813a(13) =409495053a(14) =2100558429a(15) =10836262173a(16) =56184433661a(17) =292628726205
External references
- oeis: A256939