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 A049004 #22 Sep 10 2024 18:07:41
%S A049004 10,6,13,1,13,10,10,1,19,15,14,4,10,6,13,1,13,10,10,1,19,15,14,4,10,6,
%T A049004 13,1,13,10,10,1,19,15,14,4,10,6,13,1,13,10,10,1,19,15,14,4,10,6,13,1,
%U A049004 13,10,10,1,19,15,14,4,10,6,13,1,13,10,10,1,19,15,14,4,10,6,13,1,13,10
%N A049004 First letter of English names for months of year, mapping A -> 1, B -> 2 etc.
%C A049004 Period 12: repeat [10, 6, 13, 1, 13, 10, 10, 1, 19, 15, 14, 4]. - _Joerg Arndt_, Aug 15 2014
%H A049004 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).
%e A049004 a(7)=10 because July begins with the 10th letter.
%t A049004 LetterNumber[DateValue[#,"MonthNameInitial"]]&/@DateRange[{2024,1,1},{2030,12,31},"Month"] (* or *) PadRight[{},120,{10,6,13,1,13,10,10,1,19,15,14,4}] (* _Harvey P. Dale_, Sep 10 2024 *)
%K A049004 easy,nonn,word,dumb
%O A049004 1,1
%A A049004 Deepak R. N (deepak_rama(AT)bigfoot.com)
%E A049004 Corrected a(12n+8): August starts with 'A' and not 'H'. - _Mark E. Shoulson_, Aug 15 2014
%E A049004 a(20) corrected by _Daniel Leary_, Jul 26 2016