cp's OEIS Frontend

A210666 Numbers with at least three digits in which all digits but one are the same.

%I A210666 #50 May 22 2022 14:12:20
%S A210666 100,101,110,112,113,114,115,116,117,118,119,121,122,131,133,141,144,
%T A210666 151,155,161,166,171,177,181,188,191,199,200,202,211,212,220,221,223,
%U A210666 224,225,226,227,228,229,232,233,242,244,252,255,262,266,272,277,282,288
%N A210666 Numbers with at least three digits in which all digits but one are the same.
%C A210666 Each k-digit term has k-1 appearances of a digit, d1, and 1 appearance of a different digit, d2, and k-1 >= 2 so that d1 is repeated.  Specifically, the 2-digit terms of A010784 are not terms here. - _Michael S. Branicky_, May 22 2022
%C A210666 a(n) = A031955(n+81) for n <= 244.
%C A210666 For n <= 243, i.e., the 3-digit terms, a(n) = A218556(n+10). - _M. F. Hasler_, Nov 02 2012
%H A210666 Arkadiusz Wesolowski, <a href="/A210666/b210666.txt">Table of n, a(n) for n = 1..10000</a>
%t A210666 lst = {}; Do[If[SortBy[Tally[IntegerDigits[n]], Last][[-1, -1]] == IntegerLength[n] - 1, AppendTo[lst, n]], {n, 100, 288}]; lst
%t A210666 lst = {}; Do[r = Table[a, {n}]; Do[c = FromDigits@Permutations[Join[{d}, r]]; If[d == 0, c = Rest[c]]; AppendTo[lst, c], {d, 0, 9}], {a, 0, 9}, {n, 2, 2}]; Drop[Union@Flatten[lst], 19]
%t A210666 nrepQ[n_] := Module[{dg = Select[DigitCount[n], # > 0 &]}, Length[dg] == 2 && Min[dg] == 1 && Max[dg] > 1]; Select[Range[300], nrepQ] (* _Harvey P. Dale_, Nov 20 2012 *)
%o A210666 (Python)
%o A210666 from itertools import count, islice
%o A210666 def agen(): # generator of terms
%o A210666     for d in count(3):
%o A210666         dterms = set()
%o A210666         for most in "123456789":
%o A210666             dterms.add(int(most + "0"*(d-1)))
%o A210666             for diff in "0123456789":
%o A210666                 if most == diff: continue
%o A210666                 cands = (most*i + diff + most*(d-1-i) for i in range(d))
%o A210666                 dterms.update(int(t) for t in cands if t[0] != "0")
%o A210666         yield from sorted(dterms)
%o A210666 print(list(islice(agen(), 52))) # _Michael S. Branicky_, May 17 2022
%Y A210666 Subsequence of A031955. Supersequence of A164937.
%Y A210666 Cf. A010784, A031955, A218556.
%K A210666 base,easy,nonn,less
%O A210666 1,1
%A A210666 _Arkadiusz Wesolowski_, May 08 2012