A272394 Degeneracies of entanglement witness eigenstates for 2n spin 9/2 irreducible representations.

1, 1, 10, 505, 33670, 2457190, 189442252, 15177798415, 1251216059950, 105443928375598, 9043123211156440, 786701771691580227, 69253844083218535300, 6157639918607211895000, 552193624489443516667344, 49885368826043082235592687

Offset: 0

Author

Gheorghe Coserea, Apr 28 2016

Keywords

• nonn

Links

• Gheorghe Coserea, Table of n, a(n) for n = 0..200
• Eliahu Cohen, Tobias Hansen, Nissan Itzhaki, From Entanglement Witness to Generalized Catalan Numbers, arXiv:1511.06623 [quant-ph], 2015.
• T. L. Curtright, T. S. Van Kortryk, and C. K. Zachos, Spin Multiplicities, hal-01345527, 2016.
• Vaclav Kotesovec, Recurrence (of order 5)

Crossrefs

For spin S = 1/2, 1, 3/2, 2, 5/2, 3, 7/2, 4, 9/2, 5 we get A000108, A005043, A264607, A007043, A272391, A264608, A272392, A272393, this sequence, A272395.

Programs

Mathematica

a[n_]:= 2/Pi*Integrate[Sqrt[(1-t)/t]*(4t)^n*((16t^2-20t+5)((4t-1)^2-4t))^(2n), {t, 0, 1}] (* Thomas Curtright, Jun 24 2016 *)
a[n_]:= c[0, 2 n, 9/2]-c[1, 2 n, 9/2]
c[j_, n_, s_]:= Sum[(-1)^k*Binomial[n, k]*Binomial[j - (2*s + 1)*k + n + n*s - 1, j - (2*s + 1)*k + n*s],{k, 0, Min[n, Floor[(j + n*s)/(2*s + 1)]]}] (* Thomas Curtright, Jul 26 2016 *)

PARI

N = 33; S = 9/2;
M = matrix(N+1, N*numerator(S)+1);
Mget(n, j) =  { M[1 + n, 1 + j*denominator(S)] };
Mset(n, j, v) = { M[1 + n, 1 + j*denominator(S)] = v };
Minit() = {
  my(step = 1/denominator(S));
  Mset(0, 0, 1);
  for (n = 1, N, forstep (j = 0, n*S, step,
     my(acc = 0);
     for (k = abs(j-S), min(j+S, (n-1)*S), acc += Mget(n-1, k));
     Mset(n, j, acc)));
};
Minit();
vector(1 + N\denominator(S), n, Mget((n-1)*denominator(S),0))

Formula

a(n) = (1/Pi)*int((sin(10x)/sin(x))^(2n)*(sin(x))^2,x,0,2 Pi). - Thomas Curtright, Jun 24 2016

a(n) ~ (2*sqrt(66)/1089)*10^(2n)/(sqrt(Pi)*(2n)^(3/2))(1-35/(88n) + O(1/n^2)). - Thomas Curtright, Jul 26 2016