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 A353211 #50 May 03 2022 06:45:51 %S A353211 8,39,305,1183,7271,14209,41633,64999,139679,353249,461311,936433, %T A353211 1412081,1708519,2438783,3943889,6056999,6921121,10073383,12703391, %U A353211 14196529,19471999,23725799,31367249,44260033,52025201,56270239,65534183,70573249,81517409,130064383,147241511,176128433,186640999 %N A353211 a(n) is the number of diagonalizable 2 X 2 matrices over GF(prime(n)). %H A353211 Lars Felix Lerner, <a href="/A353211/a353211_1.pdf">Diagonalizable matrices over finite fields</a> %F A353211 a(n) = (prime(n)^4 - prime(n)^2 + 2*prime(n))/2 = A101374(prime(n)). %e A353211 a(2) = 8 because there are 8 diagonalizable 2 X 2 matrices over GF(2). They are: %e A353211 1. [[0,0],[0,0]]. %e A353211 2. [[0,0],[0,1]]. %e A353211 3. [[1,0],[0,0]]. %e A353211 4. [[1,0],[0,1]]. %e A353211 5. [[1,0],[1,0]]. %e A353211 6. [[0,0],[1,1]]. %e A353211 7. [[0,1],[0,1]]. %e A353211 8. [[1,1],[0,0]]. %o A353211 (PARI) a(n) = my(p=prime(n)); (p^4 - p^2 + 2*p)/2; \\ _Michel Marcus_, May 01 2022 %Y A353211 Subsequence of A101374. %K A353211 nonn %O A353211 1,1 %A A353211 _Lars Felix Lerner_ and _Elias S. Cleusters_, Apr 30 2022