A043498 - OEIS

%I #29 Apr 24 2021 21:08:28

%S 22,122,202,212,220,221,223,224,225,226,227,228,229,232,242,252,262,

%T 272,282,292,322,422,522,622,722,822,922,1022,1122,1202,1212,1220,

%U 1221,1223,1224,1225,1226,1227,1228,1229,1232,1242,1252

%N Numbers having two 2's in base 10.

%H Daniel Starodubtsev, <a href="/A043498/b043498.txt">Table of n, a(n) for n = 1..10000</a>

%p q:= n-> numboccur(2, convert(n, base, 10))=2:

%p select(q, [$2..2222])[];  # _Alois P. Heinz_, Mar 15 2020

%t Select[Range[5000], DigitCount[#, 10, 2] == 2 &] (* _Vincenzo Librandi_, Nov 20 2015 *)

%o (PARI) c(k, d, b) = {my(c=0, f); while (k>b-1, f=k-b*(k\b); if (f==d, c++); k\=b); if (k==d, c++); return(c)}

%o for(n=0, 2000, if(c(n, 2, 10)==2, print1(n, ", "))) \\ _Altug Alkan_, Nov 20 2015

%Y Subsequence of A011532.

%K nonn,base

%O 1,1

%A _Clark Kimberling_