The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A245281 a(1)=2; for n > 1, a(n) is the least positive integer not occurring earlier that shares a digit and a factor with a(n-1). 1
 2, 12, 10, 14, 4, 24, 20, 22, 26, 6, 16, 18, 8, 28, 21, 15, 5, 25, 35, 30, 3, 33, 36, 32, 34, 38, 48, 40, 42, 27, 57, 45, 50, 52, 54, 44, 46, 56, 58, 68, 60, 62, 64, 66, 63, 39, 9, 69, 90, 70, 7, 77, 147, 49, 84, 74, 37, 333, 93, 31, 124, 72, 75, 51, 17, 102 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Is this a permutation of the integers >= 2? # Robert Israel, Sep 07 2014 LINKS Michel Lagneau, Table of n, a(n) for n = 1..3500 EXAMPLE a(16)=15 because GCD(a(16),a(15)) = GCD(15,21) = 3 and 1 is the common digit of 15 and 16. MAPLE S:= {2}: A[1]:= 2: L[1]:= {2}: for n from 2 to 1000 do   k:= 0;   mS:= max(S);   Sp:= {\$2..mS} minus S;   do      if Sp <> {} then         k:= min(Sp);         Sp:= Sp minus {k};      elif k < mS then k:= mS+1      else k:= k+1      fi;      if member(k, S) or igcd(k, A[n-1]) = 1 then next fi;      Lk:= convert(convert(k, base, 10), set);      if Lk intersect L[n-1] <> {} then         A[n]:= k;         L[n]:= Lk;         S:= S union {k};         break      fi   od: od: seq(A[n], n=1..1000); # Robert Israel, Sep 07 2014 MATHEMATICA f[s_List]:=Block[{m=s[[-1]], k=2}, While[MemberQ[s, k]||Intersection[IntegerDigits[k], IntegerDigits[m]]=={}||GCD[m, k]==1, k++]; Append[s, k]]; Nest[f, {2}, 71] CROSSREFS Cf. A064413, A184992. Sequence in context: A081468 A216349 A280015 * A308215 A216478 A181060 Adjacent sequences:  A245278 A245279 A245280 * A245282 A245283 A245284 KEYWORD nonn,base AUTHOR Michel Lagneau, Sep 06 2014 STATUS approved

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

Last modified December 5 12:51 EST 2020. Contains 338947 sequences. (Running on oeis4.)