A186024 Inverse of eigentriangle of triangle A085478.
1, -1, 1, -1, -1, 1, -1, -3, -1, 1, -1, -6, -5, -1, 1, -1, -10, -15, -7, -1, 1, -1, -15, -35, -28, -9, -1, 1, -1, -21, -70, -84, -45, -11, -1, 1, -1, -28, -126, -210, -165, -66, -13, -1, 1, -1, -36, -210, -462, -495, -286, -91, -15, -1, 1, -1, -45, -330, -924, -1287, -1001, -455, -120, -17, -1, 1
Offset: 0
Examples
Triangle begins 1, -1, 1, -1, -1, 1, -1, -3, -1, 1, -1, -6, -5, -1, 1, -1, -10, -15, -7, -1, 1, -1, -15, -35, -28, -9, -1, 1, -1, -21, -70, -84, -45, -11, -1, 1, -1, -28, -126, -210, -165, -66, -13, -1, 1, -1, -36, -210, -462, -495, -286, -91, -15, -1, 1, -1, -45, -330, -924, -1287, -1001, -455, -120, -17, -1, 1
Formula
T(n,k)=if(k
A236376 Riordan array ((1-x+x^2)/(1-x)^2, x/(1-x)^2).
1, 1, 1, 2, 3, 1, 3, 7, 5, 1, 4, 14, 16, 7, 1, 5, 25, 41, 29, 9, 1, 6, 41, 91, 92, 46, 11, 1, 7, 63, 182, 246, 175, 67, 13, 1, 8, 92, 336, 582, 550, 298, 92, 15, 1, 9, 129, 582, 1254, 1507, 1079, 469, 121, 17, 1, 10, 175, 957, 2508, 3718, 3367, 1925, 696, 154
Offset: 0
Comments
Examples
Triangle begins: 1; 1, 1; 2, 3, 1; 3, 7, 5, 1; 4, 14, 16, 7, 1; 5, 25, 41, 29, 9, 1; 6, 41, 91, 92, 46, 11, 1; 7, 63, 182, 246, 175, 67, 13, 1;
Crossrefs
Programs
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Maple
# The function RiordanSquare is defined in A321620. RiordanSquare(1+x/(1-x)^2, 8); # Peter Luschny, Mar 06 2022
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Mathematica
CoefficientList[#, y] & /@ CoefficientList[ Series[(1 - x + x^2)/(1 - 2*x - x*y + x^2), {x, 0, 12}], x] (* Wouter Meeussen, Jan 25 2014 *)
Formula
G.f.: (1 - x + x^2)/(1 - 2*x - x*y + x^2).
T(n,k) = 2*T(n-1,k) + T(n-1,k-1) - T(n-2,k), T(0,0) = T(1,0) = T(1,1) = 1, T(2,0) = 2, T(2,1) = 3, T(2,2) = 1, T(n,k) = 0 if k < 0 or k > n.
The Riordan square (see A321620) of 1 + x/(1 - x)^2. - Peter Luschny, Mar 06 2022
A177040 Irregular triangle t(n,m) = binomial(m+1,n-m) read by rows floor((n+1)/2) <= m <= n.
1, 1, 2, 1, 3, 1, 3, 4, 1, 6, 5, 1, 4, 10, 6, 1, 10, 15, 7, 1, 5, 20, 21, 8, 1, 15, 35, 28, 9, 1, 6, 35, 56, 36, 10, 1, 21, 70, 84, 45, 11, 1, 7, 56, 126, 120, 55, 12, 1, 28, 126, 210, 165, 66, 13, 1, 8, 84, 252, 330, 220, 78, 14, 1, 36, 210, 462, 495, 286, 91, 15, 1
Offset: 0
Comments
Row sums are in A052952.
Contains the right half of each row of A030528. - R. J. Mathar, May 19 2013
Examples
1; 1; 2, 1; 3, 1; 3, 4, 1; 6, 5, 1; 4, 10, 6, 1; 10, 15, 7, 1; 5, 20, 21, 8, 1; 15, 35, 28, 9, 1; 6, 35, 56, 36, 10, 1; 21, 70, 84, 45, 11, 1; 7, 56, 126, 120, 55, 12, 1; 28, 126, 210, 165, 66, 13, 1; 8, 84, 252, 330, 220, 78, 14, 1; 36, 210, 462, 495, 286, 91, 15, 1;
Programs
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Mathematica
t[n_, m_] := Binomial[m + 1, n - m]; Table[Table[t[n, m], {m, Floor[(n + 1)/2], n}], {n, 0, 15}]; Flatten[%]
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PARI
T(m,n)=binomial(n+1,m-n) \\ Charles R Greathouse IV, May 19 2013
Comments