A231010 Number of months after which a date can fall on the same day of the week, in the Julian calendar.

0, 1, 3, 6, 8, 9, 11, 14, 15, 17, 18, 19, 20, 22, 23, 26, 27, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 45, 46, 49, 52, 54, 55, 57, 58, 60, 61, 63, 64, 66, 68, 69, 71, 72, 73, 74, 75, 77, 78, 80, 81, 83, 86, 87, 89, 91, 92, 94, 95, 98, 100, 101, 103, 104, 106, 109, 110, 112

Offset

0,3

Comments

In the Julian calendar, a year is a leap year if and only if it is a multiple of 4 and all century years are leap years.

Assuming this fact, this sequence is periodic with a period of 336.

Links

Table of n, a(n) for n=0..68.

Time And Date, Repeating Months

Time And Date, Julian Calendar

Prog

(PARI) m=[0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5]; n=[31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]; y=vector(336, i, (m[((i-1)%12)+1]+((5*((i-1)\48)+(((i-1)\12)%4)-!((i-1)%48)-!((i-2)%48))))%7); x=vector(336, i, n[((i-1)%12)+1]+!((i-2)%48)); for(p=0, 336, for(q=0, 336, if(y[(q%336)+1]==y[((q+p)%336)+1], print1(p", "); break)))

Crossrefs

Cf. A230995-A231014.

Cf. A231005 (Gregorian calendar).

Sequence in context: A186385 A335155 A231005 * A285250 A188469 A005652

Adjacent sequences: A231007 A231008 A231009 * A231011 A231012 A231013

Keyword

nonn,easy

Author

Aswini Vaidyanathan, Nov 02 2013

Status

approved