A003938 Order of (usually) simple Chevalley group B_2(q), q = prime power.

720, 25920, 979200, 4680000, 138297600, 1056706560, 1721606400, 12860654400, 68518981440, 1095199948800, 1004497044480, 3057017889600, 20674026236160, 47607300000000, 102804157834560, 210103196385600

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

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.

Links

• Index entries for sequences related to groups.

Crossrefs

Cf. A000961, A003927, A003939, A003940, A003941, A003942.

Programs

Mathematica

b[q_, n_] := q^(n^2) * Product[q^(2*k) - 1, {k, 1, n}] / GCD[2, q-1]; Table[b[q, 2], {q, Select[Range[30], PrimePowerQ]}] (* Amiram Eldar, Jun 23 2025 *)

Formula

a(n) = b(A000961(n + 1), 2) where b(q,n) is defined in A003927. - Sean A. Irvine, Sep 22 2015