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
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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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 *)
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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