G.f.: Sum_{n>=0} x^n * ((1+x)^n + 1)^n / (1 + x*(1+x)^n)^(n+1).

A323680

G.f.: Sum_{n>=0} x^n * ((1+x)^n + 1)^n / (1 + x*(1+x)^n)^(n+1).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =3a(4) =10a(5) =27a(6) =109a(7) =427a(8) =1958a(9) =9467a(10) =49459a(11) =274712a(12) =1614199a(13) =9996580a(14) =64940226a(15) =441179351a(16) =3125044744a(17) =23021059143a(18) =175976694409

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