

A230999


Number of years after which it is not possible to have the same calendar for the entire year, in the Gregorian calendar.


1



1, 2, 3, 4, 5, 7, 8, 9, 10, 13, 14, 15, 16, 19, 20, 21, 24, 25, 26, 27, 30, 31, 32, 33, 35, 36, 37, 38, 41, 42, 43, 44, 47, 48, 49, 52, 53, 54, 55, 58, 59, 60, 61, 63, 64, 65, 66, 69, 70, 71, 72, 75, 76, 77, 80, 81, 82, 83, 86, 87, 88, 89, 91, 92, 93, 94, 97, 98, 99, 100
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OFFSET

1,2


COMMENTS

In the Gregorian calendar, a noncentury 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 A230996.


LINKS

Table of n, a(n) for n=1..70.
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)&&((5*(y\4)+(y%4)(y\100)+(y\400)!(y%4)+!(y%100)!(y%400))%7)==((5*((y+i)\4)+((y+i)%4)((y+i)\100)+((y+i)\400)!((y+i)%4)+!((y+i)%100)!((y+i)%400))%7), j=1)); if(j==0, print1(i", ")))


CROSSREFS

Cf. A230995A231014.
Cf. A231004 (Julian calendar).
Sequence in context: A165256 A175020 A050728 * A180590 A289342 A286302
Adjacent sequences: A230996 A230997 A230998 * A231000 A231001 A231002


KEYWORD

nonn,easy


AUTHOR

Aswini Vaidyanathan, Nov 02 2013


STATUS

approved



