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 A258442 #10 Mar 07 2016 06:12:44 %S A258442 2484,3706711688304,5696462668411740751524, %T A258442 8754305611527549602378580888144, %U A258442 13453588867526192558135312033676410914164,20675432347037054365824241005098474993236683565584,31773938310893899311445242803186409506547794898889170298404 %N A258442 9-gonal numbers (A001106) that are the sum of eight consecutive 9-gonal numbers. %H A258442 Colin Barker, <a href="/A258442/b258442.txt">Table of n, a(n) for n = 1..109</a> %H A258442 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1536796803,-1536796803,1). %F A258442 a(n) = 1536796803*a(n-1) - 1536796803*a(n-2) + a(n-3). %F A258442 G.f.: -36*x*(22897724*x^2-3074765843*x+69) / ((x-1)*(x^2-1536796802*x+1)). %F A258442 a(n) = (16014+(92323615161-65282654344*sqrt(2))*(768398401+543339720*sqrt(2))^n+(768398401+543339720*sqrt(2))^(-n)*(92323615161+65282654344*sqrt(2)))/224. - _Colin Barker_, Mar 07 2016 %e A258442 2484 is in the sequence because A001106(27) = 2484 = 111 + 154 + 204 + 261 + 325 + 396 + 474 + 559 = A001106(6) + ... + A001106(13). %o A258442 (PARI) Vec(-36*x*(22897724*x^2-3074765843*x+69) / ((x-1)*(x^2-1536796802*x+1)) + O(x^20)) %Y A258442 Cf. A001106, A258441, A258443, A258444. %K A258442 nonn,easy %O A258442 1,1 %A A258442 _Colin Barker_, May 30 2015