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 A316584 #11 Jul 10 2018 21:17:24
%S A316584 1,1,1,1,4,1,1,3,14,1,1,4,9,28,1,1,1,20,9,32,1,1,6,1,64,21,56,1,1,1,
%T A316584 30,1,184,27,58,1,1,4,1,60,25,80,171,176,1,1,3,32,1,72,1,100,33,110,1,
%U A316584 1,4,9,64,1,180,1,640,297,128,1,1,1,14,9,224,1,846,1,164,63,134,1
%N A316584 Array read by antidiagonals: T(n,k) is the number of elements x in GL(2,Z_n) with x^k == I mod n where I is the identity matrix.
%C A316584 All columns are multiplicative.
%C A316584 Some terms of this sequence may also be computed using a formula given by Kent Morrison (section 1.11 and 2.5 in the reference). See A053725 for a PARI implementation.
%H A316584 Kent E. Morrison, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL9/Morrison/morrison37.html">Integer Sequences and Matrices Over Finite Fields</a>, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.1.
%F A316584 T(n,k) = Sum_{d|k} A316566(n, d).
%F A316584 Conjecture: T(p,p) = p^2 for p prime.
%e A316584 Array begins:
%e A316584 ======================================================
%e A316584 n\k | 1 2 3 4 5 6 7 8 9 10
%e A316584 ------+-----------------------------------------------
%e A316584 1 | 1 1 1 1 1 1 1 1 1 1 ...
%e A316584 2 | 1 4 3 4 1 6 1 4 3 4 ...
%e A316584 3 | 1 14 9 20 1 30 1 32 9 14 ...
%e A316584 4 | 1 28 9 64 1 60 1 64 9 28 ...
%e A316584 5 | 1 32 21 184 25 72 1 224 21 80 ...
%e A316584 6 | 1 56 27 80 1 180 1 128 27 56 ...
%e A316584 7 | 1 58 171 100 1 846 49 184 171 58 ...
%e A316584 8 | 1 176 33 640 1 432 1 1024 33 176 ...
%e A316584 9 | 1 110 297 164 1 1566 1 272 729 110 ...
%e A316584 10 | 1 128 63 736 25 432 1 896 63 320 ...
%e A316584 11 | 1 134 111 244 1325 354 1 464 111 5950 ...
%e A316584 12 | 1 392 81 1280 1 1800 1 2048 81 392 ...
%e A316584 13 | 1 184 549 1096 1 2736 469 1408 549 184 ...
%e A316584 14 | 1 232 513 400 1 5076 49 736 513 232 ...
%e A316584 15 | 1 448 189 3680 25 2160 1 7168 189 1120 ...
%e A316584 ...
%Y A316584 Column 2 is A066907.
%Y A316584 Cf. A053725, A316566, A316586.
%K A316584 nonn,mult,tabl
%O A316584 1,5
%A A316584 _Andrew Howroyd_, Jul 07 2018