login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A026433 a(n) = least positive integer > a(n-1) and not a(i)*a(j)-1 for 1<=i<j<=n. 2

%I #11 Mar 06 2016 22:33:12

%S 2,3,4,6,8,9,10,12,13,14,16,18,20,21,22,24,28,30,32,33,34,36,37,40,42,

%T 44,45,46,48,49,50,52,54,56,57,58,60,61,64,66,68,69,70,72,74,75,76,78,

%U 80,81,82,84,85,86,88,90,92,93,94,96

%N a(n) = least positive integer > a(n-1) and not a(i)*a(j)-1 for 1<=i<j<=n.

%C Contains all members of A006093 except 1. - _Robert Israel_, Mar 06 2016

%H Ivan Neretin, <a href="/A026433/b026433.txt">Table of n, a(n) for n = 1..1000</a>

%p N:= 1000: # to get all terms <= N

%p V:= Vector(N):

%p a[1]:= 2: finished:= false:

%p for n from 2 do

%p for i from a[n-1]+1 do

%p if i > N then

%p finished:= true; break

%p elif V[i] = 0 then break

%p fi

%p od:

%p if finished then break fi;

%p a[n]:= i;

%p S:= select(`<=`,[seq(a[j]*i-1,j=1..n-1)],N);

%p if S <> [] then V[S]:= 1 fi;

%p od:

%p seq(a[i],i=1..n-1); # _Robert Israel_, Mar 06 2016

%t a = {2, 3}; used = {a[[1]]*a[[2]] - 1}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; used = Union[used, k*a - 1]; AppendTo[a, k], {n, 3, 60}]; a (* _Ivan Neretin_, Mar 06 2016 *)

%Y Cf. A026431 and references therein.

%Y Cf. A006093.

%K nonn

%O 1,1

%A _Clark Kimberling_

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 25 12:33 EDT 2024. Contains 371969 sequences. (Running on oeis4.)