A178054 Numbers representing the index of the day of week for the first day of the month in the Gregorian calendar.

6, 2, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5, 1, 4, 4, 0, 2, 5, 0, 3, 6, 1, 4, 6, 2, 5, 5, 1, 3, 6, 1, 4, 0, 2, 5, 0, 3, 6, 6, 2, 4, 0, 2, 5, 1, 3, 6, 1, 4, 0, 1, 4, 6, 2, 4, 0, 3, 5, 1, 3, 6, 2, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4, 0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5, 1, 4, 4, 0, 2, 5, 0, 3, 6, 1, 4, 6, 2, 5, 6, 2, 4, 0, 2, 5, 1

Offset: 1

Author

Lyle P. Blosser (lyleblosser(AT)att.net), May 18 2010

Keywords

• easy
• nonn

Comments

The index is 0-based, so 0 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday.

The first term in the sequence represents the day of the week index for January 1, A.D. 2000.

The sequence repeats after 4800 terms, representing 400 years in the Gregorian calendar system.

Examples

			a(1) = 6, so day of week for January 1, 2000 is Saturday; a(2) = 2, so day of week for February 1, 2000 is Tuesday; a(3) = 3, so day of week for March 1, 2000 is Wednesday.
		

References

• Arthur Benjamin and Michael Shermer, Secrets of Mental Math, First Edition, Three Rivers Press, 2006, p. 215.

Links

• Lyle P. Blosser, Table of n, a(n) for n = 1..4800
• Index entries for sequences related to calendars

Crossrefs

Cf. A178055.

Formula

a(n+1) = (a(n) + A178055(n)) (mod 7).