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 A259167 #17 Sep 08 2022 08:46:13
%S A259167 8,78408,752875208,7229107670408,69413891098384008,
%T A259167 666512175097575576008,6399849835873029582446408,
%U A259167 61451357457540654953074835208,590055927907455532986394985222408,5665716958316030570194709695030728008,54402213643694597627554069505290065112008
%N A259167 Positive octagonal numbers (A000567) that are squares (A000290) divided by 2.
%C A259167 Intersection of A000567 and A001105. - _Michel Marcus_, Jun 20 2015
%H A259167 Colin Barker, <a href="/A259167/b259167.txt">Table of n, a(n) for n = 1..251</a>
%H A259167 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9603,-9603,1).
%F A259167 G.f.: -8*x*(x^2+198*x+1) / ((x-1)*(x^2-9602*x+1)).
%e A259167 8 is in the sequence because 8 is the 2nd octagonal number, and 2*8 is the 4th square.
%t A259167 LinearRecurrence[{9603, -9603, 1}, {8, 78408, 752875208}, 20] (* _Vincenzo Librandi_, Jun 20 2015 *)
%o A259167 (PARI) Vec(-8*x*(x^2+198*x+1)/((x-1)*(x^2-9602*x+1)) + O(x^20))
%o A259167 (Magma) I:=[8, 78408, 752875208]; [n le 3 select I[n] else 9603*Self(n-1)-9603*Self(n-2)+Self(n-3): n in [1..30]]; // _Vincenzo Librandi_, Jun 20 2015
%Y A259167 Cf. A000290, A000567, A001105, A259156-A259166.
%K A259167 nonn,easy
%O A259167 1,1
%A A259167 _Colin Barker_, Jun 19 2015