A230998 Number of years after which it is not possible to have a date falling on the same day of the week, in the Gregorian calendar.

1, 2, 3, 4, 8, 9, 10, 13, 14, 15, 16, 19, 20, 21, 24, 25, 26, 27, 30, 31, 32, 36, 37, 38, 41, 42, 43, 44, 47, 48, 49, 52, 53, 54, 55, 58, 59, 60, 64, 65, 66, 69, 70, 71, 72, 75, 76, 77, 80, 81, 82, 83, 86, 87, 88, 92, 93, 94, 97, 98, 99, 100, 103, 104, 105, 109, 110, 111

Offset

1,2

Comments

In the Gregorian calendar, a non-century year is a leap year if and only if it is a multiple of 4 and a century year is a leap year if and only if it is a multiple of 400.

Assuming this fact, this sequence is periodic with a period of 400.

This is the complement of A230995.

Links

Table of n, a(n) for n=1..68.

Time And Date, Repeating Calendar

Time And Date, Gregorian Calendar

Prog

(PARI) for(i=0, 400, j=0; for(y=0, 400, if(((5*(y\4)+(y%4)-(y\100)+(y\400))%7)==((5*((y+i)\4)+((y+i)%4)-((y+i)\100)+((y+i)\400))%7), j=1)); if(j==0, print1(i", ")))

Crossrefs

Cf. A230995-A231014.

Cf. A231003 (Julian calendar).

Sequence in context: A362930 A356021 A132115 * A184810 A246293 A047228

Adjacent sequences: A230995 A230996 A230997 * A230999 A231000 A231001

Keyword

nonn,easy

Author

Aswini Vaidyanathan, Nov 02 2013

Status

approved