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A026433 a(n) = least positive integer > a(n-1) and not a(i)*a(j)-1 for 1<=i<j<=n. 2
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, 44, 45, 46, 48, 49, 50, 52, 54, 56, 57, 58, 60, 61, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 81, 82, 84, 85, 86, 88, 90, 92, 93, 94, 96 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Contains all members of A006093 except 1. - Robert Israel, Mar 06 2016

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..1000

MAPLE

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

V:= Vector(N):

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

for n from 2  do

  for i from a[n-1]+1 do

    if i > N then

      finished:= true; break

    elif V[i] = 0 then break

    fi

  od:

  if finished then break fi;

  a[n]:= i;

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

  if S <> [] then V[S]:= 1 fi;

od:

seq(a[i], i=1..n-1); # Robert Israel, Mar 06 2016

MATHEMATICA

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 *)

CROSSREFS

Cf. A026431 and references therein.

Cf. A006093.

Sequence in context: A254077 A156657 A026431 * A015858 A321473 A125292

Adjacent sequences:  A026430 A026431 A026432 * A026434 A026435 A026436

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified June 23 04:15 EDT 2021. Contains 345395 sequences. (Running on oeis4.)