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 A245783 #73 Jun 13 2015 00:55:05 %S A245783 1,2,57,166,5561,16242,544897,1591526,53394321,155953282,5232098537, %T A245783 15281830086,512692262281,1497463395122,50238609604977, %U A245783 146736130891846,4922871049025441,14378643364005762,482391124194888217,1408960313541672806,47269407300050019801 %N A245783 Numbers n such that the hexagonal number H(n) is equal to the sum of the pentagonal numbers P(m) and P(m+1) for some m. %C A245783 Also nonnegative integers y in the solutions to 6*x^2-4*y^2+4*x+2*y+2 = 0, the corresponding values of x being A122513. %H A245783 Colin Barker, <a href="/A245783/b245783.txt">Table of n, a(n) for n = 1..1000</a> %H A245783 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,98,-98,-1,1). %F A245783 a(n) = a(n-1)+98*a(n-2)-98*a(n-3)-a(n-4)+a(n-5). %F A245783 G.f.: -x*(6*x^4+11*x^3-43*x^2+x+1) / ((x-1)*(x^2-10*x+1)*(x^2+10*x+1)). %e A245783 57 is in the sequence because H(57) = 6441 = 3151+3290 = P(46)+P(47). %o A245783 (PARI) Vec(-x*(6*x^4+11*x^3-43*x^2+x+1)/((x-1)*(x^2-10*x+1)*(x^2+10*x+1)) + O(x^100)) %Y A245783 Cf. A000326, A000384, A122513. %K A245783 nonn,easy %O A245783 1,2 %A A245783 _Colin Barker_, Dec 15 2014