A003839 Order of (usually) simple Chevalley group D_n (7).
3, 28224, 2317591180800, 112554991177798901760000, 52386144472825139642572263782154240000, 14630778277213500974314928221817819519899234908241920000
Offset: 1
References
- J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites], p. xvi.
- H. S. M. Coxeter and W. O. J. Moser, Generators and Relations for Discrete Groups, 4th ed., Springer-Verlag, NY, reprinted 1984, p. 131.
Programs
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Mathematica
d[q_, n_] := q^(n*(n-1)) * (q^n-1) * Product[q^(2*k) - 1, {k, 1, n-1}] / GCD[4, q^n-1]; Table[d[7, n], {n, 1, 8}] (* Amiram Eldar, Jun 24 2025 *)
Formula
a(n) = d(7,n) where d(q,n) is defined in A003837. - Sean A. Irvine, Sep 17 2015