A362715 Triangle read by rows: T(n, k) = 2^(n-k)*(2*n)!/(2*k)! * [x^(2*n)] U[x]^(2*k), where U(x) = x*2F1([3/4, 3/4], [3/2], 4*x^2)/2F1([1/4, 1/4], [1/2], 4*x^2).
1, 0, 1, 0, 48, 1, 0, 7584, 240, 1, 0, 2515968, 97664, 672, 1, 0, 1432498176, 63221760, 560448, 1440, 1, 0, 1247557386240, 60299053056, 628024320, 2141568, 2640, 1, 0, 1542446268088320, 79885647249408, 933093697536, 3819239424, 6374368, 4368, 1
Offset: 0
Examples
The triangle begins: 1; 0, 1; 0, 48, 1; 0, 7584, 240, 1; 0, 2515968, 97664, 672, 1; 0, 1432498176, 63221760, 560448, 1440, 1; ...
Links
- Christian Krattenthaler and Thomas W. Müller, The congruence properties of Romik's sequence of Taylor coefficients of Jacobi's theta function theta_3, arXiv:2304.11471 [math.NT], 2023. See p. 6.
Programs
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Mathematica
U[x_]:=x*Hypergeometric2F1[3/4, 3/4, 3/2, 4*x^2]/Hypergeometric2F1[1/4, 1/4, 1/2, 4*x^2]; T[n_,k_]:=2^(n-k)(2n)!/(2k)!SeriesCoefficient[U[x]^(2k),{x,0,2n}]; Table[T[n,k],{n,0,7},{k,0,n}]//Flatten