13일의 금요일 공포증(Paraskavedekatriaphobia)

タイトルは、「13日の金曜日恐怖症」。英語の" paraskevidekatriaphobia"は、ギリシア語の" Paraskeví (Παρασκευή)" (金曜日の意)と "dekatreís (δεκατρείς)"に"phobía (φοβία)" (恐怖症の意)が付いて作られた。それに対し、韓国語は漢字のハングル読みでOK。
日曜日で始まる月は、13日が金曜日になる。（일요일로 시작되는 달은 13일이 금요일이 된다. ）っておくと便利、でもないか…
「どう書く？org」にR言語による13日の金曜日を数え上げるスクリプトがあって、2100年までの13日の金曜日は今日を含め157日あるらしい。

> with(as.POSIXlt(l<-(seq(Sys.Date(),as.Date("2100-12-31"),"d"))), length(print(l[mday==13 & wday==5])))
[1] "2009-11-13" "2010-08-13" "2011-05-13" "2012-01-13" "2012-04-13"
[6] "2012-07-13" "2013-09-13" "2013-12-13" "2014-06-13" "2015-02-13"
[11] "2015-03-13" "2015-11-13" "2016-05-13" "2017-01-13" "2017-10-13"
[16] "2018-04-13" "2018-07-13" "2019-09-13" "2019-12-13" "2020-03-13"
[21] "2020-11-13" "2021-08-13" "2022-05-13" "2023-01-13" "2023-10-13"
[26] "2024-09-13" "2024-12-13" "2025-06-13" "2026-02-13" "2026-03-13"
[31] "2026-11-13" "2027-08-13" "2028-10-13" "2029-04-13" "2029-07-13"
[36] "2030-09-13" "2030-12-13" "2031-06-13" "2032-02-13" "2032-08-13"
[41] "2033-05-13" "2034-01-13" "2034-10-13" "2035-04-13" "2035-07-13"
[46] "2036-06-13" "2037-02-13" "2037-03-13" "2037-11-13" "2038-08-13"
[51] "2039-05-13" "2040-01-13" "2040-04-13" "2040-07-13" "2041-09-13"
[56] "2041-12-13" "2042-06-13" "2043-02-13" "2043-03-13" "2043-11-13"
[61] "2044-05-13" "2045-01-13" "2045-10-13" "2046-04-13" "2046-07-13"
[66] "2047-09-13" "2047-12-13" "2048-03-13" "2048-11-13" "2049-08-13"
[71] "2050-05-13" "2051-01-13" "2051-10-13" "2052-09-13" "2052-12-13"
[76] "2053-06-13" "2054-02-13" "2054-03-13" "2054-11-13" "2055-08-13"
[81] "2056-10-13" "2057-04-13" "2057-07-13" "2058-09-13" "2058-12-13"
[86] "2059-06-13" "2060-02-13" "2060-08-13" "2061-05-13" "2062-01-13"
[91] "2062-10-13" "2063-04-13" "2063-07-13" "2064-06-13" "2065-02-13"
[96] "2065-03-13" "2065-11-13" "2066-08-13" "2067-05-13" "2068-01-13"
[101] "2068-04-13" "2068-07-13" "2069-09-13" "2069-12-13" "2070-06-13"
[106] "2071-02-13" "2071-03-13" "2071-11-13" "2072-05-13" "2073-01-13"
[111] "2073-10-13" "2074-04-13" "2074-07-13" "2075-09-13" "2075-12-13"
[116] "2076-03-13" "2076-11-13" "2077-08-13" "2078-05-13" "2079-01-13"
[121] "2079-10-13" "2080-09-13" "2080-12-13" "2081-06-13" "2082-02-13"
[126] "2082-03-13" "2082-11-13" "2083-08-13" "2084-10-13" "2085-04-13"
[131] "2085-07-13" "2086-09-13" "2086-12-13" "2087-06-13" "2088-02-13"
[136] "2088-08-13" "2089-05-13" "2090-01-13" "2090-10-13" "2091-04-13"
[141] "2091-07-13" "2092-06-13" "2093-02-13" "2093-03-13" "2093-11-13"
[146] "2094-08-13" "2095-05-13" "2096-01-13" "2096-04-13" "2096-07-13"
[151] "2097-09-13" "2097-12-13" "2098-06-13" "2099-02-13" "2099-03-13"
[156] "2099-11-13" "2100-08-13"
[1] 157