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%I #12 Dec 28 2017 21:42:00
%S 74,362,866,2066,2174,3974,4894,5042,5914,6626,7934,10334,10886,12634,
%T 15122,16538,17474,19238,20318,20338,20666,21974,23774,23882,24422,
%U 25094,28922,31478,33134,35138,36878,38174,41018,41774,42062,42134,46022,48502
%N Numbers n such that there are precisely 2 groups of order n and 3 of order n + 1.
%H H. U. Besche, B. Eick and E. A. O'Brien, <a href="http://dx.doi.org/10.1142/S0218196702001115">A Millennium Project: Constructing Small Groups</a>, Internat. J. Algebra and Computation, 12 (2002), 623-644.
%H Gordon Royle, <a href="http://staffhome.ecm.uwa.edu.au/~00013890/remote/cubcay/">Numbers of Small Groups</a>
%H <a href="/index/Gre#groups">Index entries for sequences related to groups</a>
%F Sequence is { n | A000001(n) = 2, A000001(n+1) = 3 }.
%e 74 is in the sequence since A000001(74) = 2 and A000001(75) = 3.
%e 362 is in the sequence since A000001(362) = 2 and A000001(363) = 3.
%e 7934 is in the sequence since A000001(7934) = 2 and A000001(7935) = 3.
%p with(GroupTheory): with(numtheory):
%p for n from 1 to 10^4 do if [NumGroups(n), NumGroups(n+1)]=[2, 3] then print(n); fi; od;
%Y Cf. A000001. Subsequence of A054395.
%K nonn
%O 1,1
%A _Muniru A Asiru_, Dec 03 2017