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.

A134207 a(0) = 2; for n > 0, a(n) = the smallest prime which is > a(n-1) such that a(n-1) + a(n) is a multiple of n.

Original entry on oeis.org

2, 3, 5, 7, 13, 17, 19, 23, 41, 67, 73, 103, 113, 173, 191, 199, 233, 277, 281, 479, 521, 571, 617, 809, 823, 827, 863, 919, 929, 1217, 1303, 1487, 1489, 1613, 1753, 2027, 2113, 2179, 2267, 2647, 2713, 3109, 3191, 3259, 3517, 3593, 3767, 3847, 3881, 4057
Offset: 0

Views

Author

Leroy Quet, Oct 14 2007

Keywords

Examples

			The primes that are > a(8)=41 form the sequence 43,47,53,59,61,67,71,... Of these, 67 is the smallest that when added to a(8)=41 gets a multiple of 9 -- 41+67 = 108 = 9*12. (41+p is not divisible by 9 for p = any prime which is > 41 and is < 67.) So a(9) = 67.
		

Crossrefs

Programs

  • Mathematica
    a = {2}; For[n = 1, n < 100, n++, i = 1; While[Not[Mod[a[[ -1]] + Prime[PrimePi[a[[ -1]]] + i], n] == 0], i++ ]; AppendTo[a, Prime[PrimePi[a[[ -1]]] + i]]]; a (* Stefan Steinerberger, Oct 17 2007 *)
  • Sage
    def A134207(max) :
        res = [2]; p = 3
        for n in range(1,max+1) :
            while (res[n-1] + p) % n != 0 : p = next_prime(p)
            res.append(p); p = next_prime(p)
        return res # Eric M. Schmidt, May 23 2013

Extensions

More terms from Stefan Steinerberger, Oct 17 2007