A166961 - OEIS

%I #18 May 31 2016 03:23:24

%S 1,1,1,1,9,1,1,59,42,1,1,361,925,154,1,1,2175,16402,8937,507,1,1,

%T 13061,265605,365050,67500,1587,1,1,78379,4127746,12611845,5592850,

%U 442242,4852,1,1,470289,62935117,398536866,365184855,68337922,2652742,14676,1

%N Triangle T(n,k) read by rows: T(n,k) = (m*n - m*k + 1)*T(n - 1, k - 1) + k*(m*k - (m - 1))*T(n - 1, k) where m = 2.

%C The general recursion relation T(n,k)= (m*n - m*k + 1)*T(n - 1, k - 1) + k*(m*k - (m - 1))*T(n - 1, k) connects several sequences for differing values of m. These are: m = 0 yields A008277, m = 1 yields A166960, m = 2 yields this sequence, and m = 3 yields A166962. These sequences are, in essence, generalized Stirling numbers of the second kind. - _G. C. Greubel_, May 29 2016

%H G. C. Greubel, <a href="/A166961/b166961.txt">Table of n, a(n) for the first 25 rows</a>

%F T(n,k)= (2*n - 2*k + 1)*T(n - 1, k - 1) + k*(2*k - 1)*T(n - 1, k).

%e Triangle starts:

%e {1},

%e {1, 1},

%e {1, 9, 1},

%e {1, 59, 42, 1},

%e {1, 361, 925, 154, 1},

%e {1, 2175, 16402, 8937, 507, 1},

%e {1, 13061, 265605, 365050, 67500, 1587, 1},

%e {1, 78379, 4127746, 12611845, 5592850, 442242, 4852, 1},

%e {1, 470289, 62935117, 398536866, 365184855, 68337922, 2652742, 14676, 1},

%e {1, 2821751, 951081090, 11977188769, 20817224001, 7796966547, 719764976, 15024830, 44181, 1}

%e ...

%t A[n_, 1] := 1; A[n_, n_] := 1; A[n_, k_] := (2*n - 2*k + 1)*A[n - 1, k - 1] + k*(2*k - 1)*A[n - 1, k]; Flatten[ Table[A[n, k], {n, 10}, {k, n}]] (* modified by _G. C. Greubel_, May 29 2016 *)

%Y Cf. A008277, A166960, A166961.

%K nonn,tabl

%O 1,5

%A _Roger L. Bagula_ and _Mats Granvik_, Oct 25 2009