login
Right-hand diagonal of A035309.
3

%I #32 Aug 30 2019 07:58:08

%S 1,1,1,10,21,483,1485,56628,225225,12317877,59520825,4304016990,

%T 24325703325,2208143028375,14230536445125,1564439686929000,

%U 11288163762500625,1463987089109939625,11665426077721040625,1749439028845202483250,15230046989184655753125

%N Right-hand diagonal of A035309.

%H Gheorghe Coserea, <a href="/A035318/b035318.txt">Table of n, a(n) for n = 0..200</a>

%F a(n) = T(n, floor(n/2)), where T(n,g) is defined by A035309. - _Gheorghe Coserea_, Mar 18 2016

%t a[0] = a[1] = 1;

%t a[n_] := a[n] = ((4n-2) Mod[n, 2] a[n-1] + (n-1)(2n-3)(2n-1) a[n-2])/(n+1);

%t Table[a[n], {n, 0, 20}] (* _Jean-François Alcover_, Aug 30 2019, from PARI *)

%o (PARI)

%o seq(N) = {

%o my(a = vector(N)); a[1] = a[2] = 1;

%o for (n = 3, N,

%o a[n] = ((4*n-2)*(n%2)*a[n-1] + (n-1)*(2*n-3)*(2*n-1)*a[n-2])/(n+1));

%o concat(1,a);

%o };

%o seq(20) \\ _Gheorghe Coserea_, Jan 20 2017

%Y Cf. A035309.

%K nonn

%O 0,4

%A _N. J. A. Sloane_.

%E More terms from _Gheorghe Coserea_, Mar 18 2016