A043498 Numbers having two 2's in base 10.

22, 122, 202, 212, 220, 221, 223, 224, 225, 226, 227, 228, 229, 232, 242, 252, 262, 272, 282, 292, 322, 422, 522, 622, 722, 822, 922, 1022, 1122, 1202, 1212, 1220, 1221, 1223, 1224, 1225, 1226, 1227, 1228, 1229, 1232, 1242, 1252

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of A011532.

Programs

Maple

q:= n-> numboccur(2, convert(n, base, 10))=2:
select(q, [$2..2222])[];  # Alois P. Heinz, Mar 15 2020

Mathematica

Select[Range[5000], DigitCount[#, 10, 2] == 2 &] (* Vincenzo Librandi, Nov 20 2015 *)

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)}
for(n=0, 2000, if(c(n, 2, 10)==2, print1(n, ", "))) \\ Altug Alkan, Nov 20 2015