OFFSET
1,5
COMMENTS
From G. C. Greubel, Feb 09 2021: (Start)
The triangle coefficients are connected to the Narayana numbers by T(n, k, q) = (1-q^n)*(A001263(n, k) - 1) + 1, for varying q values.
The row sums of this class of sequences, for varying q, is given by Sum_{k=1..n} T(n, k, q) = q^n * n + (1 - q^n)*C_{n}, where C_{n} are the Catalan numbers (A000108). (End)
LINKS
G. C. Greubel, Rows n = 1..100 of the triangle, flattened
FORMULA
T(n, k, q) = (1-q^n)*(1/k)*binomial(n-1, k-1)*binomial(n, k-1) - (1-q^n) + 1, for q = 2.
From G. C. Greubel, Feb 09 2021: (Start)
T(n, k, 2) = (1-2^n)*(A001263(n,k) - 1) + 1.
Sum_{k=1..n} T(n, k, 2) = 2^n * n + (1 - 2^n)*A000108(n). (End)
EXAMPLE
Triangle begins as:
1;
1, 1;
1, -13, 1;
1, -74, -74, 1;
1, -278, -588, -278, 1;
1, -881, -3086, -3086, -881, 1;
1, -2539, -13207, -22097, -13207, -2539, 1;
1, -6884, -49724, -124694, -124694, -49724, -6884, 1;
1, -17884, -171184, -600424, -900892, -600424, -171184, -17884, 1;
1, -45011, -551396, -2576936, -5412692, -5412692, -2576936, -551396, -45011, 1;
MATHEMATICA
T[n_, k_, q_]:= 1 + (1-q^n)*(1/k)*(Binomial[n-1, k-1]*Binomial[n, k-1] - k);
Table[T[n, k, 2], {n, 12}, {k, n}]//Flatten
PROG
(Sage)
def T(n, k, q): return 1 +(1-q^n)*(1/k)*(binomial(n-1, k-1)*binomial(n, k-1) -k)
flatten([[T(n, k, 2) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Feb 09 2021
(Magma)
T:= func< n, k, q | 1 +(1-q^n)*(1/k)*(Binomial(n-1, k-1)*Binomial(n, k-1) -k) >;
[T(n, k, 2): k in [1..n], n in [1..12]]; // G. C. Greubel, Feb 09 2021
CROSSREFS
KEYWORD
sign,tabl
AUTHOR
Roger L. Bagula, Mar 28 2010
EXTENSIONS
Edited by G. C. Greubel, Feb 09 2021
STATUS
approved