A213344 2-quantum transitions in systems of N>=2 spin 1/2 particles, in columns by combination indices.
1, 6, 24, 4, 80, 40, 240, 240, 15, 672, 1120, 210, 1792, 4480, 1680, 56, 4608, 16128, 10080, 1008, 11520, 53760, 50400, 10080, 210, 28160, 168960, 221760, 73920, 4620, 67584, 506880, 887040, 443520, 55440, 792
Offset: 2
Examples
For N=4, there are 4 second-quantum transitions with combination index 1: (0001,1110),(0010,1101),(0100,1011),(1000,0111). Starting rows of the triangle: N | k = 0, 1, ..., floor((N-2)/2) 2 | 1 3 | 6 4 | 24 4 5 | 80 40 6 | 240 240 15
References
- See A213343.
Links
- Stanislav Sykora, Table of n, a(n) for n = 2..2501
- Stanislav Sykora, T(2;N,k) with rows N=2,..,100 and columns k=0,..,floor((N-2)/2)
- Stanislav Sýkora, Magnetic Resonance on OEIS, Stan's NMR Blog (Dec 31, 2014), Retrieved Nov 12, 2019.
Crossrefs
Programs
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Mathematica
With[{q = 2}, Table[2^(n - q - 2 k)*Binomial[n, k] Binomial[n - k, q + k], {n, 12}, {k, 0, Floor[(n - 2)/2]}]] // Flatten (* Michael De Vlieger, Nov 18 2019 *)
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PARI
See A213343; set thisq = 2.
Formula
Set q = 2 in: T(q;N,k) = 2^(N-q-2*k)*binomial(N,k)*binomial(N-k,q+k).
Comments