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.

A116151 a(n) = smallest positive integer x satisfying the system of congruences { x == 1 (mod 2), x == 2 (mod 3), x == 3 (mod 5), x == 5 (mod 7), ..., x == A008578(n) (mod A008578(n+1)) }.

Original entry on oeis.org

1, 5, 23, 173, 2273, 2273, 452723, 6578843, 113275433, 3682761353, 10152454583, 5024164707833, 249908523156563, 5726413266646343, 345878207890067123, 15103232990013860963, 1905274424667036455303, 111502614383457156882293
Offset: 1

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Author

Christian Bjartli (cbjartli(AT)gmail.com), Apr 14 2007

Keywords

Comments

Minimum Chinese Remainder Prime Modulus Ladder: for the n-th term, the number modulus a prime equals the previous prime for the first n primes (the initial term is defined to be 1). - Fred Schneider, Oct 21 2007

Examples

			a(3)=23 because that is the smallest number such that n==1 (mod 2), n==2 (mod 3) and n == 3 (mod 5).
		

Crossrefs

Cf. A070198.

Programs

  • Maple
    Primes:= [1,seq(ithprime(i),i=1..30)]:
    seq(chrem(Primes[1..k],Primes[2..k+1]),k=1..30); # Robert Israel, Oct 26 2018
  • Mathematica
    Table[ChineseRemainder[Join[{1},Prime[Range[n-1]]],Prime[Range[n]]],{n,20}] (* Harvey P. Dale, Mar 30 2018 *)
  • PARI
    { a(n) = lift(chinese(vector(n,i,Mod(if(i==1,1,prime(i-1)),prime(i))))) }; vector(30,n,a(n)) \\ Max Alekseyev, Apr 16 2007
    
  • PARI
    my(z=Mod(1,2)); forprime(x=3,100,z=chinese(z,Mod(precprime(x-1),x)); print1(lift(z), ", ")); \\ Fred Schneider, Oct 21 2007

Extensions

More terms from Max Alekseyev, Apr 16 2007
Edited by N. J. A. Sloane, May 05 2007
Further edited by N. J. A. Sloane, Jun 30 2008 at the suggestion of R. J. Mathar and Christian Bjartli.