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A327348
The 66 prime dates in each non-leap year of the form concatenate (month,day) without leading zeros for days.
6
11, 13, 17, 19, 113, 127, 131, 23, 29, 211, 223, 227, 31, 37, 311, 313, 317, 331, 41, 43, 47, 419, 421, 53, 59, 521, 523, 61, 67, 613, 617, 619, 71, 73, 79, 719, 727, 83, 89, 811, 821, 823, 827, 829, 97, 911, 919, 929, 101, 103, 107, 109, 1013, 1019, 1021, 1031, 113, 1117, 1123, 1129, 127, 1213, 1217, 1223, 1229, 1231
OFFSET
1,1
COMMENTS
The months m = 1, 2, ..., 12 contribute 7, 5, 6, 5, 4, 5, 5, 7, 4, 8, 4, 6 such dates respectively. This adds up to 66 prime dates. In leap years there is the additional date 229 (see A327349).
MATHEMATICA
Select[Flatten@ Array[Function[{m, d}, Array[FromDigits[Join[m, IntegerDigits[#]]] &, d]] @@ {IntegerDigits@ #, Which[MemberQ[{4, 6, 9, 11}, #], 30, # == 2, 28, True, 31]} &, 12], PrimeQ] (* Michael De Vlieger, Oct 03 2019 *)
CROSSREFS
Cf. A327346 (74 prime dates of the form d.m (no leading 0's for m and d), A327347 (55 prime dates of the form d.m with leading 0's for m = 1, 3, 7, 9), A327349 (leap year case), A327914 (58 prime dates of the form m.d in non-leap years, with leading 0 for d = 1..9), A327915 (59 prime dates like A327914 but for leap years).
Sequence in context: A032591 A088265 A356987 * A327349 A240899 A090149
KEYWORD
nonn,easy,fini,full
AUTHOR
Wolfdieter Lang, Sep 30 2019
STATUS
approved