A097296 Numbers n such that A001055(n) divides n.

1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 17, 19, 20, 22, 23, 26, 27, 28, 29, 30, 31, 34, 36, 37, 38, 41, 43, 44, 46, 47, 48, 52, 53, 56, 58, 59, 61, 62, 67, 68, 70, 71, 73, 74, 76, 79, 82, 83, 86, 89, 92, 94, 97, 101, 103, 105, 106, 107, 109, 110, 113, 116, 118, 122, 124, 127, 130

Offset

1,2

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

Florian Luca, Anirban Mukhopadhyay and Kotyada Srinivas, On the Oppenheim's "factorisatio numerorum" function

Formula

Luca et al. estimate the density of this sequence (see their Theorem 3).

Maple

g:= proc(n, k) option remember; `if`(n>k, 0, 1)+
      `if`(isprime(n), 0, add(`if`(d>k, 0, g(n/d, d)),
         d=numtheory[divisors](n) minus {1, n}))
    end:
a:= proc(n) option remember; local k;
      for k from 1+`if`(n=1, 0, a(n-1))
      while irem(k, g(k$2))>0 do od; k
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, May 16 2014

Mathematica

g[n_, k_] := g[n, k] = If[n > k, 0, 1] + If[PrimeQ[n], 0, Sum[If[d > k, 0, g[n/d, d]], {d, Divisors[n] // Most // Rest}]]; a[1] = 1; a[n_] := (For[k = 1 + If[n == 1, 0, a[n-1]], Mod[k, g[k, k]] > 0 , k++]; k); Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Oct 07 2014, after Alois P. Heinz *)

Crossrefs

Sequence in context: A279455 A050687 A098908 * A131616 A175857 A173919

Adjacent sequences: A097293 A097294 A097295 * A097297 A097298 A097299

Keyword

nonn

Author

N. J. A. Sloane, Jun 12 2009

Status

approved