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 A181886 #4 Mar 30 2012 18:57:11 %S A181886 0,1,0,5,3,0,22,15,4,0,94,66,21,6,0,399,282,92,31,8,0,1691,1197,393, %T A181886 137,41,9,0,7164,5073,1668,586,181,47,11,0,30348,21492,7069,2488,773, %U A181886 208,57,12,0,128557,91044 %N A181886 Lower Beatty array of the golden ratio, (1+sqrt(5))/2. %C A181886 Upper and lower Beatty arrays are defined at A181661. %C A181886 (row 1)=A049652. %C A181886 (column 1)=A000004. %C A181886 (column 2)=A000201 (lower Wythoff sequence). %C A181886 (column 3)=u(l(n))+l(u(n)), or simply ul+lu. %C A181886 (column 4)=u(ul+lu)+l(uu+ll), %C A181886 whereas column 4 of the upper Beatty array is %C A181886 u(uu+ll)+l(ul+lu). %C A181886 U(n,k)-L(n,k)=n for n>=1, k>=0. %e A181886 Northwest corner of the array: %e A181886 0....1....5....22....94....399... %e A181886 0....3...15....66...282...1197... %e A181886 0....4...21....92...393...1668... %e A181886 0....6...31...137...586...2488... %Y A181886 Cf. A181661, A000201, A001950, A000045. %K A181886 nonn,tabl %O A181886 1,4 %A A181886 _Clark Kimberling_, Nov 19 2010