A230325 (prime(n)^2 -1)*(prime(n)^2 - prime(n))/2.

3, 24, 240, 1008, 6600, 13104, 39168, 61560, 133584, 341040, 446400, 911088, 1377600, 1668744, 2386848, 3869424, 5954280, 6807600, 9922968, 12524400, 14001984, 19225440, 23439864, 31014720, 43803648, 51510000, 55723824, 64921608, 69925680, 80795904, 129040128

Offset: 1

Author

Jonathan Vos Post, Oct 16 2013

Keywords

• nonn
• easy

Comments

The number of unordered bases of a (F_p)-vector space of dimension 2, p prime.

Examples

			a(25) = (p^2 -1)*(p^2 - p)/2 for p = prime(25) = (97^2 -1)*(97^2 - 97)/2 = 43803648.
		

Links

• Mark Herman, Jonathan Pakianathan, Ergun Yalcin, On a canonical construction of tesselated surfaces via finite group theory, Part I, arXiv:1310.3848v1 [math.GT], Oct 14, 2013, see p.34.

Crossrefs

Cf. A000040.

Programs

Mathematica

Table[p = Prime[n]; (p^2 - 1)*(p^2 - p)/2, {n, 50}] (* T. D. Noe, Oct 18 2013 *)

Formula

(p^2 -1)*(p^2 - p)/2 for p = 2, 3, 5, 7, 11, 13... for p = prime(n).