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A035318 Right-hand diagonal of A035309.

%I A035318 #34 Jul 08 2025 21:32:47
%S A035318 1,1,1,10,21,483,1485,56628,225225,12317877,59520825,4304016990,
%T A035318 24325703325,2208143028375,14230536445125,1564439686929000,
%U A035318 11288163762500625,1463987089109939625,11665426077721040625,1749439028845202483250,15230046989184655753125
%N A035318 Right-hand diagonal of A035309.
%H A035318 Gheorghe Coserea, <a href="/A035318/b035318.txt">Table of n, a(n) for n = 0..200</a>
%F A035318 a(n) = T(n, floor(n/2)), where T(n,g) is defined by A035309. - _Gheorghe Coserea_, Mar 18 2016
%t A035318 a[0] = a[1] = 1;
%t A035318 a[n_] := a[n] = ((4n-2) Mod[n, 2] a[n-1] + (n-1)(2n-3)(2n-1) a[n-2])/(n+1);
%t A035318 Table[a[n], {n, 0, 20}] (* _Jean-François Alcover_, Aug 30 2019, from PARI *)
%o A035318 (PARI)
%o A035318 seq(N) = {
%o A035318   my(a = vector(N)); a[1] = a[2] = 1;
%o A035318   for (n = 3, N,
%o A035318        a[n] = ((4*n-2)*(n%2)*a[n-1] + (n-1)*(2*n-3)*(2*n-1)*a[n-2])/(n+1));
%o A035318   concat(1,a);
%o A035318 };
%o A035318 seq(20)  \\ _Gheorghe Coserea_, Jan 20 2017
%Y A035318 Cf. A035309.
%K A035318 nonn
%O A035318 0,4
%A A035318 _N. J. A. Sloane_
%E A035318 More terms from _Gheorghe Coserea_, Mar 18 2016