cp's OEIS Frontend

A215876 Numbers that contain each decimal digit at least twice.

%I A215876 #13 Feb 25 2019 17:27:55
%S A215876 10012233445566778899,10012233445566778989,10012233445566778998,
%T A215876 10012233445566779889,10012233445566779898,10012233445566779988,
%U A215876 10012233445566787899,10012233445566787989,10012233445566787998,10012233445566788799
%N A215876 Numbers that contain each decimal digit at least twice.
%C A215876 A subsequence of A171102. Contains A000079 o A215830, i.e., { 2^A215830(n); n=1,2,3... }, as a subsequence.
%C A215876 The first 17!/2^8 ~ 1.4e12 terms are of the form 10^19 + x, where x runs over all permutations of the digits 12233445566788799, up to 99887766554433221.
%H A215876 Robert Israel, <a href="/A215876/b215876.txt">Table of n, a(n) for n = 1..10000</a>
%p A215876 nextp:= proc(L) local m, i,j, r, rj;
%p A215876 for m from 2 while L[m-1] <= L[m] do od:
%p A215876 r:= 10:
%p A215876 for j from 1 to m-1 do
%p A215876    if L[j] > L[m] and L[j] < r then
%p A215876       r:= L[j]; rj:= j;
%p A215876    fi
%p A215876 od;
%p A215876 [ op(sort([seq(L[i],i={$1..m} minus {rj})],`>`)), r,seq(L[i],i=m+1..nops(L))]
%p A215876 end proc:
%p A215876 A[1]:= 10012233445566778899:
%p A215876 L:= convert(A[1],base,10):
%p A215876 for n from 2 to 100 do
%p A215876   L:= nextp(L);
%p A215876   A[n]:= add(L[i]*10^(i-1),i=1..nops(L));
%p A215876 od:
%p A215876 seq(A[i],i=1..100); # _Robert Israel_, Feb 25 2019
%o A215876 (PARI) is_A215876(N)={my(c=vector(10)); for(k=1,#N=Vecsmall(Str(N)), c[N[k]-47]++); vecmin(c)>1}
%K A215876 nonn,base,look
%O A215876 1,1
%A A215876 _M. F. Hasler_, Aug 25 2012