This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A229738 #30 Sep 08 2022 08:46:06
%S A229738 14,63,425,1519,8591,16393,46529,71839,151823,377609,491071,987049,
%T A229738 1480961,1787983,2542559,4092713,6262319,7148041,10374079,13061231,
%U A229738 14585473,19964959,24297503,32072129,45172609,53055401,57362863,66759119,71868169,82960193,132112639,149489471,178699649,189326479,249739049
%N A229738 a(n) = p^2*(p^2+2*p-1)/2, where p = prime(n).
%H A229738 Bruno Berselli, <a href="/A229738/b229738.txt">Table of n, a(n) for n = 1..1000</a>
%H A229738 L. Kaylor, D. Offner, <a href="https://projecteuclid.org/euclid.involve/1513733722">Counting matrices over a finite field with all eigenvalues in the field</a>, Involve, a Journal of Mathematics, Vol. 7 (2014), No. 5, 627-645. [<a href="http://dx.doi.org/10.2140/involve.2014.7.627">DOI</a>]
%H A229738 Michael Knapp, <a href="http://www.maa.org/sites/default/files/mathmag145-147-knapp02283.pdf">Two by Two Matrices with Both Eigenvalues in Z/pZ</a>, Math. Mag., Vol. 79, No. 2, April 2006.
%H A229738 G. Olsavsky, <a href="http://www.jstor.org/stable/3219091">The Number of 2 by 2 Matrices over Z/pZ with Eigenvalues in the Same Field</a>, Math. Mag., 76 (2003), 314-317.
%t A229738 Table[Prime[n]^2 (Prime[n]^2 + 2 Prime[n] - 1)/2, {n, 40}] (* _Bruno Berselli_, Oct 07 2013 *)
%t A229738 #^2 (#^2+2#-1)/2&/@Prime[Range[40]] (* _Harvey P. Dale_, Mar 13 2017 *)
%o A229738 (Magma) [p^2*(p^2+2*p-1)/2: p in PrimesUpTo(200)]; // _Bruno Berselli_, Oct 07 2013
%o A229738 (PARI) a(n)=p=prime(n);p^2*(p^2+2*p-1)/2 \\ _Anders Hellström_, Sep 04 2015
%o A229738 (PARI) lista(nn) = forprime(p=2, nn, print1(p^2*(p^2+2*p-1)/2, ", ")); \\ _Michel Marcus_, Sep 04 2015
%Y A229738 Cf. A229739, A255499.
%K A229738 nonn
%O A229738 1,1
%A A229738 _N. J. A. Sloane_, Oct 05 2013