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 A260915 Prime number days: prime numbers that can be interpreted as an ISO date. 1
 10000103, 10000121, 10000223, 10000303, 10000511, 10000609, 10000721, 10000723, 10000813, 10000819, 10000831, 10001009, 10001107, 10001119, 10001203, 10001207, 10001209, 10001213, 10001221, 10001227, 10001231, 10010101, 10010113, 10010213, 10010227, 10010311, 10010317, 10010323, 10010401 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS An ISO date is in the format YYYY-MM-DD. The last term of this sequence is 99991207. LINKS Christian Perfect, Table of n, a(n) for n = 1..24974 EXAMPLE 20150821 belongs to this sequence because it is prime and represents the 21st of August 2015. MATHEMATICA d = Sort@ Join[Flatten[Plus[{100, 300, 500, 700, 800, 1000, 1200}, #] & /@ Select[Range[1, 31, 2], ! Mod[#, 5] == 0 &]], Flatten[Plus[{200, 400, 600, 900, 1100}, #] & /@ Select[Range[1, 29, 2], ! Mod[#, 5] == 0 &]]]; Select[Flatten[Plus[If[Or[Mod[#, 10000000] == 0, Mod[#, 40000] == 0 && ! Mod[#, 1000000] == 0], d, Delete[d, 25]], #] & /@ (10000 Range[1000, 1001])], PrimeQ] (* Michael De Vlieger, Aug 04 2015 *) PROG (Python) import datetime . def prime_number_days(): ...j = 0 ...date = datetime.date(1000, 1, 1) ...while date.year<2100: ......x = int(date.strftime("%Y%m%d")) ......while primes[j]

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Last modified May 24 18:12 EDT 2022. Contains 354043 sequences. (Running on oeis4.)