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A291312 Numbers that contain exactly one pair of identical digits x and a triple of identical digits y (x not equal y). 0

%I #14 Jan 19 2019 04:15:43

%S 10001,10010,10011,10100,10101,10110,11000,11001,11010,11100,11122,

%T 11133,11144,11155,11166,11177,11188,11199,11212,11221,11222,11313,

%U 11331,11333,11414,11441,11444,11515,11551,11555,11616,11661,11666,11717,11771,11777,11818,11881,11888,11919,11991,11999,12112,12121,12122,12211,12212,12221

%N Numbers that contain exactly one pair of identical digits x and a triple of identical digits y (x not equal y).

%C Since other digits may be present, the last term is 9998876543210; otherwise the last term would be 99988 (as communicated by _Giovanni Resta_).

%t ok[n_] := Block[{d = DigitCount[n]}, Count[d, 2] == 1 == Count[d, 3] && {} == Select[d, # > 3 &]]; Select[Range[22200], ok] (* _Giovanni Resta_, Aug 25 2017 *)

%K nonn,base,fini

%O 1,1

%A _Enrique Navarrete_, Aug 21 2017

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Last modified March 29 11:14 EDT 2024. Contains 371278 sequences. (Running on oeis4.)