

A074940


Numbers having at least one 2 in their ternary representation.


36



2, 5, 6, 7, 8, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 29, 32, 33, 34, 35, 38, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 83, 86, 87, 88, 89, 92
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OFFSET

1,1


COMMENTS

Also, numbers n such that 3 divides C(2n,n).
Also, numbers n such that coefficient of x^n equals 0 in prod(k>=0, 1x^(3^k))


LINKS



FORMULA



EXAMPLE

12 is not in the sequence since it is 110 in base 3, but 11 is in the sequence since it is 102 in base 3  Michael B. Porter, Jun 30 2016


MATHEMATICA

Select[Range@ 120, MemberQ[IntegerDigits[#, 3], 2] &] (* or *)
Select[Range@ 120, Divisible[Binomial[2 #, #], 3] &] (* Michael De Vlieger, Jun 29 2016 *)
Select[Range[100], DigitCount[#, 3, 2]>0&] (* Harvey P. Dale, Aug 25 2019 *)


PROG

(Haskell)
a074940 n = a074940_list !! (n1)
a074940_list = filter ((== 0) . a039966) [0..]


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



