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Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j * binomial(n-2*j,j)/(n-2*j)!.
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%I #24 Apr 16 2023 09:48:55

%S 1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,3,5,1,1,1,1,4,9,11,1,1,1,1,5,13,

%T 21,31,1,1,1,1,6,17,31,81,106,1,1,1,1,7,21,41,151,351,337,1,1,1,1,8,

%U 25,51,241,736,1233,1205,1,1,1,1,9,29,61,351,1261,2689,5769,5021,1

%N Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j * binomial(n-2*j,j)/(n-2*j)!.

%H Seiichi Manyama, <a href="/A362043/b362043.txt">Antidiagonals n = 0..139, flattened</a>

%F E.g.f. of column k: exp(x + k*x^3/6).

%F T(n,k) = T(n-1,k) + k * binomial(n-1,2) * T(n-3,k) for n > 2.

%F T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j / (j! * (n-3*j)!).

%e Square array begins:

%e 1, 1, 1, 1, 1, 1, 1, ...

%e 1, 1, 1, 1, 1, 1, 1, ...

%e 1, 1, 1, 1, 1, 1, 1, ...

%e 1, 2, 3, 4, 5, 6, 7, ...

%e 1, 5, 9, 13, 17, 21, 25, ...

%e 1, 11, 21, 31, 41, 51, 61, ...

%e 1, 31, 81, 151, 241, 351, 481, ...

%o (PARI) T(n, k) = n!*sum(j=0, n\3, (k/6)^j/(j!*(n-3*j)!));

%Y Columns k=0..2 give A000012, A190865, A001470.

%Y Main diagonal gives A362173.

%Y T(n,2*n) gives A362300.

%Y T(n,6*n) gives A362301.

%Y Cf. A359762, A362302.

%K nonn,tabl

%O 0,14

%A _Seiichi Manyama_, Apr 15 2023