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 A190653 Years with exactly three "Friday the 13ths", starting from 1901. 4
 1903, 1914, 1925, 1928, 1931, 1942, 1953, 1956, 1959, 1970, 1981, 1984, 1987, 1998, 2009, 2012, 2015, 2026, 2037, 2040, 2043, 2054, 2065, 2068, 2071, 2082, 2093, 2096, 2099, 2105, 2108, 2111, 2122, 2133, 2136, 2139, 2150, 2161, 2164, 2167, 2178, 2189, 2192 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 Eric Weisstein's World of Mathematics, Triskaidekaphobia Wikipedia, Triskaidekaphobia Index entries for sequences related to calendars FORMULA A101312(a(n)) = 3, 1 <= A101312(n) <= 3. EXAMPLE 2012 is a term, since only Jan 13 2012, Apr 13 2012 and Jul 13 2012 fell on Fridays. MATHEMATICA Module[{mos={#[[1]], Length[#]}&/@(Flatten[Take[#, 1]&/@DateSelect[ DateRange[ {1900, 1, 1}, {2200, 12, 1}], #Day==13&&#DayName== Friday&]]// Split)}, Select[ mos, #[[2]]>2&][[All, 1]]] (* Requires Mathematica version 12 or later *) (* Harvey P. Dale, Jan 17 2021 *) PROG (Haskell) a190653 n = a190653_list !! (n-1) a190653_list = filter ((== 3) . a101312) [1901..] (Python) from datetime import date def ok(n): return sum(date.isoweekday(date(n, m, 13)) == 5 for m in range(1, 13)) == 3 print(list(filter(ok, range(1901, 2193)))) # Michael S. Branicky, Sep 12 2021 CROSSREFS Cf. A101312, A190651, A190652. Sequence in context: A273913 A190651 A237787 * A124628 A253364 A112947 Adjacent sequences: A190650 A190651 A190652 * A190654 A190655 A190656 KEYWORD nonn AUTHOR Reinhard Zumkeller, May 16 2011 STATUS approved

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Last modified December 1 21:21 EST 2023. Contains 367502 sequences. (Running on oeis4.)