# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a327347 Showing 1-1 of 1 %I A327347 #16 May 27 2024 12:22:55 %S A327347 101,401,601,701,1201,1301,1601,1801,1901,2801,3001,103,503,1103,1303, %T A327347 2003,2203,2503,2803,2903,107,307,607,907,1307,1607,1907,2207,2707, %U A327347 109,409,509,709,809,1009,1109,1409,1609,1709,2309,2609,2909,211,311,811,911,1511,1811,2011,2111,2311,2411,2711,3011 %N A327347 The 54 prime dates of each year of the form concatenate(day,month) with leading zero for months 1, 3, 7, 9 (no leading zero for days). %C A327347 All these dates come from January, March, July, September and November, sorted this d.m way, with 11, 9, 9, 13 and 12 dates, respectively, summing to 54. Note that all September dates without leading zero of month m = 9 from A327346 survive after inserting the 0. The November dates coincide, of course. %t A327347 Select[Flatten@ Map[Function[{m, d}, Array[FromDigits[IntegerDigits[#]~Join~m] &, d]] @@ {PadLeft[IntegerDigits@ #, 2], Which[MemberQ[{4, 6, 9, 11}, #], 30, # == 2, 28, True, 31]} &, Select[Range[1, 12, 2], CoprimeQ[#, 10] &]], PrimeQ] (* _Michael De Vlieger_, Oct 03 2019 *) %Y A327347 Cf. A062800 (first 11 members), A101780 (9 members, starting with n = 2), A166547 (9 members, starting with n = 2), A166560 (first 13 members), A167442 (12 members, starting with n = 2), respectively. %Y A327347 Cf. A327346 (74 prime dates d.m without leading 0 for month), A327348 (66 prime dates m.d for non-leap years), A327349 (67 prime dates, like A327348 but for leap years), A327914 (58 prime dates m.d for non-leap years, with leading 0 for d = 1..9), A327915 (59 prime dates, like A327914, but for leap years). %K A327347 nonn,easy,fini,full %O A327347 1,1 %A A327347 _Wolfdieter Lang_, Sep 30 2019 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE