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 A073305 #6 Nov 29 2020 18:07:01
%S A073305 366,335,306,275,245,214,184,153,122,92,61,31,0
%N A073305 Remaining days in leap year at end of n-th month.
%C A073305 a(0)=A073304(0)+1 and a(1)=A073304(1)+1; these sequences otherwise are identical since there is only one leap day and it is in the second month.
%e A073305 a(1)=335 because there are 335 days left in a leap year at the end of January, the first month.
%t A073305 Join[{366},(DateDifference[#,{2016,12,31}]&/@Table[Select[Table[ DatePlus[ {2016,m,1},{d,"Day"}],{d,30}],#[[2]]==m&][[-1]],{m,12}])[[All,1]]] (* _Harvey P. Dale_, Nov 29 2020 *)
%Y A073305 Cf. A073304 (remaining days in non-leap year), A061251 (elapsed days at end of n-th month beginning with non-leap year).
%K A073305 fini,full,nonn
%O A073305 0,1
%A A073305 _Rick L. Shepherd_, Jul 23 2002