This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A327914 #18 Sep 01 2023 11:30:13
%S A327914 101,103,107,109,113,127,131,211,223,227,307,311,313,317,331,401,409,
%T A327914 419,421,503,509,521,523,601,607,613,617,619,701,709,719,727,809,811,
%U A327914 821,823,827,829,907,911,919,929,1009,1013,1019,1021,1031,1103,1109,1117,1123,1129,1201,1213,1217,1223,1229,1231
%N A327914 The 58 prime dates of each non-leap year of the form concatenate(month,day) with leading zero for days 1..9.
%C A327914 All these dates come in non-leap years from the months January, February, ..., December, in the form m.d, with a 0 in front of the days 1..9, with 7, 3, 5, 4, 4, 5, 4, 6, 4, 5, 5, 6 prime dates, respectively, adding up to 58. For the corresponding leap year case with 59 prime dates see A327915.
%C A327914 Comparing with A327914 (no leap year, no 0 in front of days d = 1..9) one finds the number differences for the months 0, -2, -1, -2+1 = -1, 0, 0, -1, -1, -1+1 = 0, -3, +1, -1+1 = 0, respectively. For a month with difference 0 (Jan, May, Jun) one just has to add a zero before the days 1..9 in A327914. In the other cases a -x indicates that x dates are no longer prime after insertion of a 0 before days 1..9, and +1 indicates that a new prime date appears: Feb: 203 and 209 out, Mar: 301 out, Apr: 403 and 407 out, 409 in, Jul: 703 out, Aug: 803 out, Sep: 907 out, 901 in, Oct 101, 103 and 107 out, Nov: 1109 in, Dec: 1207 out, 1201 in.
%t A327914 Select[Flatten@ Array[Function[{m, d}, Array[FromDigits[m~Join~PadLeft[IntegerDigits[#], 2]] &, d]] @@ {IntegerDigits@ #, Which[MemberQ[{4, 6, 9, 11}, #], 30, # == 2, 28, True, 31]} &, 12], PrimeQ] (* _Michael De Vlieger_, Oct 03 2019 *)
%t A327914 fd[{m_,d_}]:=FromDigits[Flatten[{m,PadLeft[{d},2,0]}]]; Select[fd[Take[#,{2,3}]]&/@ DateRange[ {2023,1,1},{2023,12,31}],PrimeQ] (* _Harvey P. Dale_, Sep 01 2023 *)
%Y A327914 Cf. A327346 (74 prime dates d.m without leading 0 for month), A327347 (54 prime dates d.m with leading 0 for months m = 1, 3, 7, 9), A327348 (66 prime dates m.d for non-leap years), A327349 (67 prime dates, like A327348 but for leap years), A327915 (59 prime dates, for leap years).
%K A327914 nonn,easy,fini,full
%O A327914 1,1
%A A327914 _Wolfdieter Lang_, Sep 30 2019
%E A327914 a(39) corrected by _Seth A. Troisi_, May 18 2022