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A125680 Blue moon years > 2000 (new definition), listed with multiplicity, i.e., once for each month having two full moons. 0
2001, 2004, 2007, 2009, 2012, 2015, 2018, 2018, 2020, 2023, 2026, 2028, 2031, 2034, 2037, 2037, 2039, 2042, 2045, 2048, 2050, 2053, 2056, 2058, 2061, 2064, 2066, 2067, 2069, 2072, 2075, 2077, 2080, 2083, 2085, 2088, 2091, 2094, 2094, 2096, 2099, 2102 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A blue moon is the second full moon to occur in a single calendar month. The sequence contains the (Gregorian) years during which each succeeding blue moon will occur.

This is a new version of the definition. The original definition is that of the third full moon in a season which has four. All of the definitions depend on the longitude of the observer. Unless specified otherwise, we should assume that we refer to UTC. A special subsequence is that of the years (1999, 2018, 2037, ...) in which there is no full moon in February, which usually implies that there are two in January as well as in March. This happens most often at an interval of 19 years, but sometimes also 8 or 11 years, for example in 1589, 1608, 1627, 1646, 1665, 1676, 1684, 1695, 1714, 1741, 1752, 1760, 1771, 1790, 1798, 1809, 1828, 1847, 1866... - M. F. Hasler, Dec 08 2017

REFERENCES

Philip Hiscock, Folklore of the Blue Moon, MUN Folklore & Language Archive, Memorial University of Newfoundland, St John's, Newfoundland A1B 3X8, Canada

Donald W. Olson, What's a Blue Moon?, Sky & Telescope (Archives); May 1999; 36;

Donald W. Olson, Richard T. Fienberg and Roger W. Sinnott, What's a Blue Moon?, Sky & Telescope, (Archives); Jul 2004; 134;

LINKS

Table of n, a(n) for n=1..42.

David Harper, Blue moon calculator.

Phillip Hiscock, Folklore of the Blue Moon, International Planetarium Society, 1993.

Wikipedia, Blue Moon

Index entries for sequences related to calendars

EXAMPLE

a(7) = 2018 because at least one blue moon will occur that year.

a(8) = 2018 because after the first blue moon in January, a second blue moon occurs in March of that year.

CROSSREFS

Sequence in context: A048517 A048518 A043416 * A162238 A162239 A104400

Adjacent sequences:  A125677 A125678 A125679 * A125681 A125682 A125683

KEYWORD

nonn

AUTHOR

H. Lee Price, Jan 30 2007

EXTENSIONS

Edited by M. F. Hasler, Dec 08 2017

STATUS

approved

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Last modified November 12 12:43 EST 2018. Contains 317109 sequences. (Running on oeis4.)