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%I #10 Oct 18 2013 14:21:17
%S 3,24,240,1008,6600,13104,39168,61560,133584,341040,446400,911088,
%T 1377600,1668744,2386848,3869424,5954280,6807600,9922968,12524400,
%U 14001984,19225440,23439864,31014720,43803648,51510000,55723824,64921608,69925680,80795904,129040128
%N (prime(n)^2 -1)*(prime(n)^2 - prime(n))/2.
%C The number of unordered bases of a (F_p)-vector space of dimension 2, p prime.
%H Mark Herman, Jonathan Pakianathan, Ergun Yalcin, <a href="http://arxiv.org/abs/1310.3848">On a canonical construction of tesselated surfaces via finite group theory, Part I</a>, arXiv:1310.3848v1 [math.GT], Oct 14, 2013, see p.34.
%F (p^2 -1)*(p^2 - p)/2 for p = 2, 3, 5, 7, 11, 13... for p = prime(n).
%e a(25) = (p^2 -1)*(p^2 - p)/2 for p = prime(25) = (97^2 -1)*(97^2 - 97)/2 = 43803648.
%t Table[p = Prime[n]; (p^2 - 1)*(p^2 - p)/2, {n, 50}] (* _T. D. Noe_, Oct 18 2013 *)
%Y Cf. A000040.
%K nonn,easy
%O 1,1
%A _Jonathan Vos Post_, Oct 16 2013