A081606 Numbers having at least one 1 in their ternary representation.

1, 3, 4, 5, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 21, 22, 23, 25, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 75, 76, 77, 79, 81, 82, 83, 84, 85, 86

Offset

1,2

Comments

Complement of A005823.

Integers m such that central Delannoy number A001850(m) == 0 (mod 3). - Emeric Deutsch and Bruce E. Sagan, Dec 04 2003

Integers m such that A026375(m) == 0 (mod 3). - Fabio Visonà, Aug 03 2023

Links

Table of n, a(n) for n=1..71.

Johann Cigler, Some elementary observations on Narayana polynomials and related topics, arXiv:1611.05252 [math.CO], 2016. See p.25.

Mathematics Stack Exchange, Proof that integers m in this sequence are such that A026375(m) == 0 (mod 3).

Mathematica

Select[Range[100], DigitCount[#, 3, 1]>0&] (* Harvey P. Dale, Nov 26 2022 *)

Prog

(Python)
from itertools import count, islice
def A081606_gen(): # generator of terms
    a = 0
    for n in count(1):
        b = int(bin(n)[2:], 3)<<1
        yield from range(a+1, b)
        a = b
A081606_list = list(islice(A081606_gen(), 30)) # Chai Wah Wu, Oct 13 2023

Crossrefs

Cf. A007089, A062756, A081609, A081605, A074940.

Sequence in context: A180152 A162610 A155935 * A079945 A283736 A039017

Adjacent sequences: A081603 A081604 A081605 * A081607 A081608 A081609

Keyword

nonn,base

Author

Reinhard Zumkeller, Mar 23 2003

Extensions

More terms from Emeric Deutsch and Bruce E. Sagan, Dec 04 2003

Status

approved