Expansion of g.f.: (1-3*z-sqrt(1-6*z+5*z^2+8*z^3-4*z^4))/(2*z^2*(1-z)).
A256938
Expansion of g.f.: (1-3*z-sqrt(1-6*z+5*z^2+8*z^3-4*z^4))/(2*z^2*(1-z)).
Terms
- a(0) =1a(1) =2a(2) =7a(3) =24a(4) =86a(5) =316a(6) =1189a(7) =4562a(8) =17796a(9) =70398a(10) =281812a(11) =1139658a(12) =4649402a(13) =19112962a(14) =79096155a(15) =329258424a(16) =1377798890a(17) =5792421108a(18) =24454224310a(19) =103631241912a(20) =440674939192
External references
- oeis: A256938