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 A195291 #32 Jan 01 2019 16:29:37
%S A195291 1,2,3,5,6,7,9,10,11,13,14,15,17,18,19,21,22,23,25,26,27,29,30,31,33,
%T A195291 34,35,37,38,39,41,42,43,45,46,47,49,50,51,53,54,55,57,58,59,61,62,63,
%U A195291 65,66,67,69,70,71,73,74,75,77,78,79,81,82,83,85,86,87,89,90,91,93,94,95,97,98,99,100
%N A195291 Years in the Gregorian calendar which are not (proleptic) leap years.
%C A195291 If n does not exactly divide 100, n should exactly divide 4.
%C A195291 If n exactly divides 100, n should exactly divide 400.
%H A195291 <a href="/index/Rec#order_304">Index entries for linear recurrences with constant coefficients</a>, order 304.
%H A195291 <a href="/index/Ca#calendar">Index entries for sequences related to calendars</a>
%F A195291 a(n) = a(n-1) + a(n-303) - a(n-304). [_Charles R Greathouse IV_, Sep 18 2011]
%t A195291 Select[Range[100],!LeapYearQ[{#}]&] (* _Harvey P. Dale_, Jan 01 2019 *)
%o A195291 (PARI) is(n)=n%4||(n%100==0&&n%400) \\ _Charles R Greathouse IV_, Sep 18 2011
%Y A195291 Cf. A042968.
%K A195291 nonn,easy
%O A195291 1,2
%A A195291 _Kausthub Gudipati_, Sep 16 2011