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 A301720 #27 Nov 16 2023 13:40:57
%S A301720 1,6,9,18,21,24,36,36,39,54,51,54,72,66,69,90,81,84,108,96,99,126,111,
%T A301720 114,144,126,129,162,141,144,180,156,159,198,171,174,216,186,189,234,
%U A301720 201,204,252,216,219,270,231,234,288,246,249,306,261,264,324,276,279,342,291,294,360,306,309,378,321
%N A301720 Coordination sequence for node of type V1 in "krb" 2-D tiling (or net).
%C A301720 Linear recurrence and g.f. confirmed by Shutov/Maleev link. - _Ray Chandler_, Aug 30 2023
%D A301720 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987. See Table 2.2.1, page 66, 1st row, 2nd tiling.
%H A301720 Ray Chandler, <a href="/A301720/b301720.txt">Table of n, a(n) for n = 0..1000</a>
%H A301720 Brian Galebach, <a href="http://probabilitysports.com/tilings.html">Collection of n-Uniform Tilings</a>. See Number 19 from the list of 20 2-uniform tilings.
%H A301720 Brian Galebach, <a href="/A250120/a250120.html">k-uniform tilings (k <= 6) and their A-numbers</a>
%H A301720 Reticular Chemistry Structure Resource (RCSR), <a href="http://rcsr.net/layers/krb">The krb tiling (or net)</a>
%H A301720 Anton Shutov and Andrey Maleev, <a href="https://doi.org/10.1515/zkri-2020-0002">Coordination sequences of 2-uniform graphs</a>, Z. Kristallogr., 235 (2020), 157-166. See supplementary material, krb, vertex u_1.
%H A301720 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,2,0,0,-1).
%F A301720 G.f.: -(-x^6-6*x^5-9*x^4-16*x^3-9*x^2-6*x-1)/(x^6-2*x^3+1). - _N. J. A. Sloane_, Mar 29 2018
%t A301720 LinearRecurrence[{0,0,2,0,0,-1},{1,6,9,18,21,24,36},100] (* _Paolo Xausa_, Nov 16 2023 *)
%Y A301720 Cf. A301722.
%Y A301720 Coordination sequences for the 20 2-uniform tilings in the order in which they appear in the Galebach catalog, together with their names in the RCSR database (two sequences per tiling): #1 krt A265035, A265036; #2 cph A301287, A301289; #3 krm A301291, A301293; #4 krl A301298, A298024; #5 krq A301299, A301301; #6 krs A301674, A301676; #7 krr A301670, A301672; #8 krk A301291, A301293; #9 krn A301678, A301680; #10 krg A301682, A301684; #11 bew A008574, A296910; #12 krh A301686, A301688; #13 krf A301690, A301692; #14 krd A301694, A219529; #15 krc A301708, A301710; #16 usm A301712, A301714; #17 krj A219529, A301697; #18 kre A301716, A301718; #19 krb A301720, A301722; #20 kra A301724, A301726.
%K A301720 nonn,easy
%O A301720 0,2
%A A301720 _N. J. A. Sloane_, Mar 26 2018
%E A301720 a(11)-a(100) from _Davide M. Proserpio_, Mar 28 2018