A023694 Numbers with exactly 3 1's in ternary expansion.

13, 31, 37, 39, 41, 43, 49, 67, 85, 91, 93, 95, 97, 103, 109, 111, 113, 115, 117, 119, 123, 125, 127, 129, 131, 133, 139, 145, 147, 149, 151, 157, 175, 193, 199, 201, 203, 205, 211, 229, 247, 253, 255, 257, 259, 265, 271, 273, 275, 277, 279, 281, 285, 287, 289

Offset: 1

Author

Olivier Gérard

Keywords

• nonn
• base
• easy

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000

Programs

Maple

q:= n-> numboccur(1, convert(n, base, 3))=3:
select(q, [$1..300])[];  # Alois P. Heinz, Mar 15 2020

Mathematica

Select[ Range[ 270 ], (Count[ IntegerDigits[ #, 3 ], 1 ]==3)& ]