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 A060871 #22 Dec 26 2024 14:31:46
%S A060871 6,384,19494,960000,47073606,2306841984,113036904294,5538819840000,
%T A060871 271402252867206,13298710955443584,651636840771389094,
%U A060871 31930205225480640000,1564580056242329380806,76664422757230585805184,3756556715113793827473894,184071279040642363407360000
%N A060871 Number of n X n matrices over GF(7) with rank 1.
%H A060871 Harry J. Smith, <a href="/A060871/b060871.txt">Table of n, a(n) for n = 1..200</a>
%H A060871 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (57,-399,343).
%F A060871 a(n) = (7^n - 1)^2/6.
%F A060871 G.f.: -6*x*(7*x+1) / ((x-1)*(7*x-1)*(49*x-1)). - _Colin Barker_, Dec 23 2012
%e A060871 a(2) = 384 because there are 385 (the second element in sequence A060721) singular 2 X 2 matrices over GF(7), that have rank <= 1 of which only the zero matrix has rank zero so a(2) = 385 - 1 = 384.
%o A060871 (PARI) a(n) = { (7^n - 1)^2 / 6 } \\ _Harry J. Smith_, Jul 13 2009
%Y A060871 Cf. A060721.
%K A060871 nonn,easy
%O A060871 1,1
%A A060871 Ahmed Fares (ahmedfares(AT)my-deja.com), May 04 2001
%E A060871 More terms from Larry Reeves (larryr(AT)acm.org), May 07 2001