A377293 - OEIS

%I #23 Dec 30 2024 02:19:42

%S 1,2,3,4,5,6,7,8,9,10,11,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,

%T 12,12,12,11,11,10,10,8,8,6,6,5,3,3,1,1

%N Number of days where month plus day equals n, in a non-leap year in the Gregorian calendar.

%C Sum of all terms gives 365.

%e For n=4 three dates (1st of March, 2nd of February, 3rd of January) sum to n, so a(4) = 3.

%p (p-> add(coeff(p, x, i), i=2..degree(p)))(add(add(x^(i+j), j=1..

%p [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31][i]), i=1..12));  # _Alois P. Heinz_, Dec 27 2024

%o (Python)

%o sequence = []

%o for year in range(2, 43):

%o     current_count = 0

%o     for month, days_in_month in zip(range(1, 13), (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)):

%o         for day in range(1, days_in_month + 1):

%o             if month + day == year:

%o                 current_count += 1

%o     sequence += [current_count]

%Y Cf. A008685.

%K nonn,dumb,easy,fini,full,new

%O 2,2

%A _Manuel Biwer_, Dec 27 2024