A075076 Integers pertaining to A075075: a(n) = b(n-1)*b(n+1)/b(n) where b(n) is the n-th term of A075075.

2, 3, 2, 10, 6, 4, 15, 6, 20, 12, 12, 30, 12, 28, 6, 33, 14, 7, 44, 13, 14, 34, 26, 15, 51, 18, 55, 36, 24, 55, 20, 56, 30, 30, 56, 39, 36, 68, 52, 42, 85, 40, 77, 60, 45, 77, 42, 99, 56, 56, 99, 72, 80, 54, 57, 30, 46, 38, 29, 23, 62, 58, 37, 31, 82, 74, 38, 123, 38, 86, 114, 39

Offset

2,1

Comments

This is not a permutation of the natural numbers since a(4)=a(2), a(9)=a(6), a(12)=a(11) etc. [From Hagen von Eitzen, May 16 2009]

Links

Alois P. Heinz, Table of n, a(n) for n = 2..10000

Maple

c:= proc() false end:
b:= proc(n) option remember; local k, m;
       if n<3 then k:=n
     else m:= denom(b(n-2) /b(n-1));
          for k from m by m while c(k) do od
       fi;
       c(k):= true; k
    end:
a:= n-> b(n-1)*b(n+1)/b(n):
seq(a(n), n=2..100);  # Alois P. Heinz, Jul 18 2012

Mathematica

Clear[b, c]; c[_] = False; b[n_] := b[n] = Module[{k, m}, If[n<3, k = n, m = Denominator[b[n-2]/b[n-1]]; For[k = m, c[k], k = k+m]]; c[k] = True; k]; a[n_] := b[n-1]*b[n+1]/b[n]; Table[a[n], {n, 2, 100}] (* Jean-François Alcover, Jun 10 2015, after Alois P. Heinz *)

Crossrefs

Cf. A075075.

Sequence in context: A126286 A126288 A205393 * A333129 A078828 A247170

Adjacent sequences: A075073 A075074 A075075 * A075077 A075078 A075079

Keyword

nonn,look

Author

Amarnath Murthy, Sep 09 2002

Extensions

More terms from Sascha Kurz, Feb 03 2003

Status

approved