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a(n) = A142458(n, 1 + floor(n/2)).
1

%I #6 Mar 17 2022 01:10:46

%S 1,1,8,39,546,5482,109640,1709675,44451550,947113254,30307624128,

%T 821539580358,31218504053604,1028949571999572,45273781167981168,

%U 1758747856988046771,87937392849402338550,3935893923685215214030

%N a(n) = A142458(n, 1 + floor(n/2)).

%H G. C. Greubel, <a href="/A154425/b154425.txt">Table of n, a(n) for n = 1..375</a>

%F a(n) = A142458(n, 1 + floor(n/2)).

%t T[n_, k_, m_]:= T[n, k, m]= If[k==1 || k==n, 1, (m*n-m*k+1)*T[n-1, k-1, m] + (m*k-m+1)*T[n-1, k, m]];

%t A154425[n_]:= T[n, 1+Floor[n/2], 3];

%t Table[A154425[n], {n, 30}] (* modified by _G. C. Greubel_, Mar 16 2022 *)

%o (Sage)

%o @CachedFunction

%o def T(n,k,m): # A142458

%o if (k==1 or k==n): return 1

%o else: return (m*(n-k)+1)*T(n-1,k-1,m) + (m*k-m+1)*T(n-1,k,m)

%o def A154425(n): return T(n, 1 + (n//2), 3)

%o [A154425(n) for n in (1..30)] # _G. C. Greubel_, Mar 16 2022

%Y Cf. A142458.

%K nonn

%O 1,3

%A _Roger L. Bagula_, Jan 09 2009

%E Edited by _G. C. Greubel_, Mar 16 2022