

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(n1).


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
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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[n1]) = 1 then next fi;
Lk:= convert(convert(k, base, 10), set);
if Lk intersect L[n1] <> {} 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



