A141287 Years in which there are five Fridays in the month of February.

1760, 1788, 1828, 1856, 1884, 1924, 1952, 1980, 2008, 2036, 2064, 2092, 2104, 2132, 2160, 2188, 2228, 2256, 2284, 2324, 2352, 2380, 2408, 2436, 2464, 2492, 2504, 2532, 2560, 2588, 2628, 2656, 2684, 2724, 2752, 2780, 2808, 2836, 2864, 2892, 2904, 2932

Offset: 1

Author

J. Lowell, Aug 01 2008

Keywords

• nonn
• easy

Links

• Index entries for sequences related to calendars
• Index entries for linear recurrences with constant coefficients, signature (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1).

Crossrefs

Cf. A119406 (Sun), A135795 (Mon), A143994 (Tue), A141039 (Wed), A143995 (Thu), A176478 (Sat).

Programs

Maple

A141287 := proc(n) nper := (n-1) mod 14 ; floor((n-1)/14)*400+op(1+nper ,[1760, 1788, 1828, 1856, 1884, 1924, 1952, 1980, 2008, 2036, 2064, 2092, 2104, 2132]) ; end proc: seq(A141287(n),n=1..80) ; # R. J. Mathar, Jan 25 2010

Mathematica

(* First do *) Needs["Calendar`"] (* then *) fQ[y_] := Mod[y, 4] == 0 && Mod[y, 400]!=0 && DayOfWeek[{y, 2, 1}] == Friday; Select[Range[1750, 3051], fQ@# &] (* Robert G. Wilson v, Jun 11 2010 *)
(* Second program, needing Mma version >= 9.0 *)
okQ[y_] := Mod[y, 4] == 0 && DayCount[{y, 1, 31}, DatePlus[{y, 3, 1}, -1], Friday] == 5;
Select[Range[1752, 3051, 4], okQ] (* Jean-François Alcover, Mar 27 2020 *)

Extensions

More terms using the 400-year periodicity of the Gregorian calendar by R. J. Mathar, Jan 25 2010