cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A104034 Years between occurrences of Easter on the 25th of the month in the Gregorian calendar.

Original entry on oeis.org

3, 8, 57, 3, 8, 141, 3, 8, 49, 8, 84, 3, 8, 57, 84, 3, 8, 57, 3, 8, 57, 3, 8, 73, 3, 8, 73, 68, 11, 3, 8, 46, 3, 8, 141, 3, 8, 84, 3, 8, 46, 11, 3, 8, 49, 8, 73, 11, 3, 54, 3, 8, 84, 3, 8, 46, 3, 8, 84, 68, 3, 8, 46, 11, 3, 8, 73, 3, 8, 141, 11, 3, 8, 46, 3, 8, 57, 84, 3, 8, 84, 3, 8, 46, 11
Offset: 1583

Views

Author

Cino Hilliard, Mar 31 2005

Keywords

Comments

Easter was celebrated on the 25th in 1742. It was not celebrated on the 25th again until 1883, 141 years later.

Programs

  • PARI
    edate(yr1,yr2,day) = { local(flag=1,d,y,y2,ct,dt); for(d=day,day, ct=0; for(y=yr1,yr2, dt=oudin(y); if(eval(mid(dt,4,2))==d, if(flag,y2=y;flag=0); ct++; print1(y-y2","); if(y2<>y,y2=y); ); ); \ print(d","ct); ) } oudin(y) = \This is based on the algorithm of Oudin (1940) { local(c,n,k,i1,i2,i3,a1,a2,m,d,l,dt,dat=""); c=floor(y/100); n=y-19*floor(y/19); k=floor((c-17)/25); i1=c-floor(c/4)-floor((c-k)/3)+19*n+15; i2=i1-30*floor(i1/30); i3=i2-floor(i2/28)*(1-floor(i2/28)*floor(29/(i2+1))*floor((21-n)/11)); a1=y+floor(y/4)+i3+2-c+floor(c/4); a2=a1-7*floor(a1/7); l=i3-a2; m=3+floor((l+40)/44); d=l+28-31*floor(m/4); dat = concat(dat,right(Str(m+100),2)); dat = concat(dat," "); dat = concat(dat,right(Str(d+100),2)); dat = concat(dat," "); dat = concat(dat,Str(y)); return(dat); }

Formula

The formula is based on the algorithm of Oudin (1940) taken from the link.