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 A219113 #23 Nov 07 2015 13:38:26 %S A219113 1,61,5941,582121,57041881,5589522181,547716131821,53670591396241, %T A219113 5259170240699761,515345012997180301,50498552103482969701, %U A219113 4948342761128333850361,484887092038473234365641,47513986677009248633982421,4655885807254867892895911581 %N A219113 Sequence of integers which are simultaneously a sum of consecutive squares and a difference of consecutive cubes. %H A219113 <a href="http://primepuzzles.net/puzzles/puzz_662.htm">Puzzle 662</a> %H A219113 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (99,-99,1). %F A219113 a(n) = 3*A105038(n)*(A105038(n)+1)+1. %F A219113 G.f.: -x*(x^2-38*x+1) / ((x-1)*(x^2-98*x+1)). [_Colin Barker_, Nov 21 2012] %F A219113 a(n) = (6+(5-2*sqrt(6))^(2*n-1)+(5+2*sqrt(6))^(2*n-1))/16. - _Gerry Martens_, Jun 06 2015 %F A219113 a(n) = 98*a(n-1)-a(n-2)-36, n>=3. - _R. J. Mathar_, Nov 07 2015 %e A219113 1 = 0^2+1^2 = 1^3-0^3. %e A219113 61 = 5^2+6^2 = 5^3-4^3. %o A219113 (PARI) A(n)=my(v=[0,4],k,a);a=if(n<3,v[n],for(k=3,n,v=concat(v,v[#v]*10-v[#v-1]+4));v[#v]);3*a*(a+1)+1 %Y A219113 Cf. A105038. %K A219113 nonn,easy %O A219113 1,2 %A A219113 _Igor Schein_, Nov 12 2012