A078921 Signed variant of A077012.
1, -1, 2, 2, -3, 6, -6, 8, -12, 24, 24, -30, 40, -60, 120, -120, 144, -180, 240, -360, 720, 720, -840, 1008, -1260, 1680, -2520, 5040, -5040, 5760, -6720, 8064, -10080, 13440, -20160, 40320, 40320, -45360, 51840, -60480, 72576, -90720, 120960, -181440, 362880, -362880, 403200, -453600, 518400, -604800, 725760, -907200, 1209600, -1814400, 3628800
Offset: 1
Examples
Triangle starts: 1 -1, 2 2, -3, 6 -6, 8, -12, 24 24, -30, 40, -60, 120 -120, 144, -180, 240, -360, 720 720, -840, 1008, -1260, 1680, -2520, 5040 ...
Programs
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Mathematica
Table[Table[ -(-1)^(n-k+1) n/(n-k+1), {k, 1, n}] (n-1)!, {n, 1, 12}]
Formula
T(n, k) = -(-1)^(n-k+1)*(n/(n-k+1))*(n-1)!.
E.g.f.: log(1+x)/(1-y*x). - Vladeta Jovovic, Feb 07 2003
Sum_{n>=1} Sum_{k=1..n} 1/T(n, k) = (e^2+1)/(4*e). - Amiram Eldar, Jun 29 2025
Comments