%I #7 Dec 23 2014 15:37:01
%S 0,0,1,3,7,28,131,26465,2832610615,18602165186505644,
%T 1577146952504975321253720851
%N Number of exponent-7 class 2 groups of order 7^n.
%H J. H. Conway, Heiko Dietrich and E. A. O'Brien, <a href="http://www.math.auckland.ac.nz/~obrien/research/gnu.pdf">Counting groups: gnus, moas and other exotica</a>.
%H Bettina Eick and E. A. O'Brien, <a href="http://www.math.auckland.ac.nz/~obrien/research/count-pgroups.pdf">Enumerating p-groups</a>. Group theory. J. Austral. Math. Soc. Ser. A 67 (1999), no. 2, 191-205.
%H E. A. O'Brien, <a href="https://www.math.auckland.ac.nz/~obrien/research/bibliography.pdf">Bibliography on the determination of finite groups</a>.
%Y Cf. A090140, A252784, A252785, A252786.
%K nonn,hard,more
%O 0,4
%A _Eric M. Schmidt_, Dec 21 2014