OFFSET
1,1
COMMENTS
Period 12: repeat [7, 8, 5, 5, 3, 4, 4, 6, 9, 7, 8, 8].
According to the definition this should strictly speaking be finite: there is no 13th month of the year. But for several reasons we prefer to see this as an infinite periodic sequence. - M. F. Hasler, Mar 05 2018
REFERENCES
GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 60.
LINKS
Time and Date, A Calendar website.
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,1).
FORMULA
From Elmo R. Oliveira, Jul 18 2024: (Start)
G.f.: x*(7 + 8*x + 5*x^2 + 5*x^3 + 3*x^4 + 4*x^5 + 4*x^6 + 6*x^7 + 9*x^8 + 7*x^9 + 8*x^10 + 8*x^11)/(1 - x^12).
a(n) = a(n-12) for n > 12. (End)
EXAMPLE
a(1) = 7 because January has 7 letters.
MATHEMATICA
PadRight[{}, 72, {7, 8, 5, 5, 3, 4, 4, 6, 9, 7, 8, 8}] (* or *)
Array[StringLength@ DateString[DateObject[{0, Mod[#, 12] + 1, 1, 0, 0, 0}, "Month"], {"MonthName"}] &, 72, 0] (* Michael De Vlieger, Feb 25 2018 *)
PROG
(PARI) A031139(n)=digits(879644355878)[12-n%12] \\ M. F. Hasler, Mar 05 2018
CROSSREFS
KEYWORD
nonn,word,easy
AUTHOR
Dmitri Papichev (Dmitri.Papichev(AT)iname.com)
STATUS
approved