# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a366697 Showing 1-1 of 1 %I A366697 #9 Oct 17 2023 08:19:27 %S A366697 1,4,15,94,706,5769,49923,449376,4164228,39459852,380594767, %T A366697 3724049805,36876008673,368835076813,3720863181033,37815675159285, %U A366697 386818379566749,3979362306753315,41144521893563511,427335033811660713,4456402044181677264 %N A366697 G.f. satisfies A(x) = (1 + x)^3 + x*A(x)^3. %F A366697 a(n) = Sum_{k=0..n} binomial(3*(2*k+1),n-k) * binomial(3*k,k)/(2*k+1). %o A366697 (PARI) a(n) = sum(k=0, n, binomial(3*(2*k+1), n-k)*binomial(3*k, k)/(2*k+1)); %Y A366697 Cf. A366266, A366696. %Y A366697 Cf. A364623. %K A366697 nonn %O A366697 0,2 %A A366697 _Seiichi Manyama_, Oct 16 2023 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE