A044995 Numbers whose base-3 representation contains exactly one 0 and one 2.

6, 11, 15, 19, 21, 32, 34, 38, 42, 46, 48, 58, 64, 66, 95, 97, 103, 113, 115, 119, 123, 127, 129, 139, 145, 147, 175, 193, 199, 201, 284, 286, 292, 310, 338, 340, 346, 356, 358, 362, 366, 370, 372, 382, 388, 390, 418, 436, 442, 444

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

F:= proc(n) local i, j, t;
t:= (3^n-1)/2;
op(sort([seq(seq(t - 3^i + 3^j, i= {$0..j-1, $j+1..n-2}), j=0..n-1)]))
end proc:
map(F, [$2..7]); # Robert Israel, Mar 11 2020

Mathematica

Select[Range[500], DigitCount[#, 3, 0]==DigitCount[#, 3, 2]==1&] (* Harvey P. Dale, Sep 04 2023 *)

Prog

(Python)
from sympy.ntheory import count_digits
def ok(n): d = count_digits(n, 3); return d[0] == 1 and d[2] == 1
print(list(filter(ok, range(500)))) # Michael S. Branicky, Jun 11 2021

Crossrefs

Subsequence of A039276.

Cf. A007089, A005823.

Sequence in context: A315394 A043098 A039276 * A135708 A315395 A315396

Adjacent sequences: A044992 A044993 A044994 * A044996 A044997 A044998

Keyword

nonn,base,look

Author

Clark Kimberling

Status

approved