cp's OEIS Frontend

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.

A327346 The 74 prime dates of each year of the form concatenate(day,month) without leading zeros for month (and day), sorted by date, including duplicates.

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%I A327346 #25 May 31 2023 15:38:24
%S A327346 11,31,41,61,71,101,131,151,181,191,211,241,251,271,281,311,13,23,43,
%T A327346 53,73,83,103,113,163,173,193,223,233,263,283,293,313,17,37,47,67,97,
%U A327346 107,127,137,157,167,197,227,257,277,307,317,19,29,59,79,89,109,139,149,179,199,229,239,269,211,311,811,911,1511,1811,2011,2111,2311,2411,2711,3011
%N A327346 The 74 prime dates of each year of the form concatenate(day,month) without leading zeros for month (and day), sorted by date, including duplicates.
%C A327346 All these prime dates come from January, March, July, September and November, in the form d.m with no 0 in front of the months m = 1, 3, 7, and 9, with 16, 17, 16, 13 and 12 dates, respectively, which sum to 74.
%C A327346 There are just two duplicates, 211 (Jan. 21 and Nov. 2) and 311 (Jan. 31 and Nov. 3).
%t A327346 Select[Flatten@ Array[Function[{m, d}, Array[FromDigits[IntegerDigits[#]~Join~m] &, d]] @@ {IntegerDigits@ #, Which[MemberQ[{4, 6, 9, 11}, #], 30, # == 2, 28, True, 31]} &, 12], PrimeQ] (* _Michael De Vlieger_, Oct 03 2019 *)
%Y A327346 Cf. A030430 (first 16 members), A030431 (17 members, starting with n = 2), A030432 (16 members starting with n = 2), A030433 (first 13 members), A167442 (12 members starting with n = 2).
%Y A327346 Cf. 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), A327914 (58 prime dates m.d in non-leap years, with leading 0 for d = 1..9), A327915 (59 prime dates, like A327914, but for leap years).
%K A327346 nonn,easy,fini,full
%O A327346 1,1
%A A327346 _Wolfdieter Lang_, Sep 30 2019