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A231004 Number of years after which it is not possible to have the same calendar for the entire year, in the Julian calendar. 1
1, 2, 3, 4, 5, 7, 8, 9, 10, 12, 13, 14, 15, 16, 18, 19, 20, 21, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 35, 36, 37, 38, 40, 41, 42, 43, 44, 46, 47, 48, 49, 51, 52, 53, 54, 55, 57, 58, 59, 60, 61, 63, 64, 65, 66, 68, 69, 70, 71, 72, 74, 75, 76, 77, 79, 80, 81, 82, 83, 85, 86, 87 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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 28.

This is the complement of A231001.

LINKS

Table of n, a(n) for n=1..72.

Time And Date, Repeating Calendar

Time And Date, Julian Calendar

PROG

(PARI) for(i=0, 420, j=0; for(y=0, 420, if(((5*(y\4)+(y%4))%7)==((5*((y+i)\4)+((y+i)%4))%7)&&((5*(y\4)+(y%4)-!(y%4))%7)==((5*((y+i)\4)+((y+i)%4)-!((y+i)%4))%7), j=1)); if(j==0, print1(i", ")))

CROSSREFS

Cf. A230995-A231014.

Cf. A230999 (Gregorian calendar).

Sequence in context: A039224 A161508 A039264 * A039161 A032797 A001967

Adjacent sequences:  A231001 A231002 A231003 * A231005 A231006 A231007

KEYWORD

nonn,easy

AUTHOR

Aswini Vaidyanathan, Nov 02 2013

STATUS

approved

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Last modified November 12 14:43 EST 2019. Contains 329058 sequences. (Running on oeis4.)