Limerick

(12+144+20 + 3 4**(1/2))/7 + 5*11 = 9**2 + 0

A dozen, a gross, and a score,
Plus three times the square root of four,
Divided by seven
Plus five times eleven
Is nine squared and naught a bit more.

I'm trying to relate this limerick to calendrics. 
The first sum works out to 182, which is half a year.
Dividing by seven gives number of weeks in 1/2 year.

I'm not yet sure what to do about the rest. Anyway, thinking
about this has got me starting to think of a calendar related
item for as many integers as possible, along these lines:

2: days in a weekend
4: quarters in a year
5: days in a work week
7: days in a week
8: years in an Octaetris
11: years after which Easter is ofter the same
12: months in Julian/Gregorian calendar year
12: lunar months in a Islamic year
13: months in calendar year with 28 day months
13: lunar months in a lunisolar long year
14: days in two weeks (fortnight)
14: lunar months in a full moon cycle (approx)
15: lunar months in a short yerm
16: full moon cycles in a Saros
17: lunar months in a full yerm
19: years in a Metonic cycle
19: days in a Bahai month and Bahai months in a year
28: years in a Julian cycle with days of week
28: days in month of 13 month calendar
28: days in February in a common year
29: days in February in a leap year
29: days in a short lunar month
30: days in a long lunar month
30: days in April, June, September or November
31: days in any other Gregorian or Julian month
38: eclipse seasons in a Saros
49: 364-day years in a Jubilee
49: lunar months reckoned to be 1447 days
52: weeks in a year (approx)
55: weeks in an abundant long lunisolar year
61: eclipse seasons in an Inex
99: lunar months in an Octaetris
183: number of 49-month cycles in 725 years
223: lunar months in a Saros
235: lunar months in a Metonic cycle
260: days in a Mayan Tzolkin
293: solar years in six jubilees
334: years reckoned to be 4131 lunar months
353: years reckoned to be 4366 lunar months
353: days in a deficient short lunisolar year
354: days in a regular short lunisolar year
355: days in a abundant short lunisolar year
358: lunar months in an Inex
364: days in 52 weeks
365: days in a solar common year
366: days in a solar leap year
383: days in a deficient long lunisolar year
384: days in a regular long lunisolar year
385: days in a abundant long lunisolar year
391: years reckoned to be 403 lunar years
     and also 824 eclipse seasons (Palmen cycle)
443: days in a short yerm
502: days in a full yerm
532: years in a Julian Easter cycle
725: years in 183 49-month cycles
850: lunar months in a 52-yerm cycle
945: days in a week of weeks
1447: days in a 49-month cycle (lunar)
1461: days in 4 years including a leap year
4131: lunar months in 334-year cycle
4366: lunar months in 353-year cycle
6686: Martian days in a Martian 10-year cycle
10631: days in a Tabular Islamic 30-year cycle
12053: days in a 33-year cycle with 8 leap years
17836: days in a Jubilee (49 364-day years)
18980: days in a Mayan calendar round
20871: weeks in a Gregorian 400-year cycle
25101: days in a 52-yerm cycle
27759: days in a Callypic 76-year cycle
107016: days in six jubilee cycle (294 364-day years)
121991: days in 334-year cycle (approx)
146097: days in a Gregorian 400-year cycle

etc.

The goal is to have something for as many numbers as possible.
If you'd like to add entries yourself, feel free to upload an
amended version of this file.

I've added many.  Karl Palmen 2002-08-07