login
A178054
Numbers representing the index of the day of week for the first day of the month in the Gregorian calendar.
4
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
1,1
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.
REFERENCES
Arthur Benjamin and Michael Shermer, Secrets of Mental Math, First Edition, Three Rivers Press, 2006, p. 215.
FORMULA
a(n+1) = (a(n) + A178055(n)) (mod 7).
EXAMPLE
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.
CROSSREFS
Cf. A178055.
Sequence in context: A090425 A160081 A240937 * A195453 A259543 A256632
KEYWORD
easy,nonn
AUTHOR
Lyle P. Blosser (lyleblosser(AT)att.net), May 18 2010
STATUS
approved