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A226636 Numbers whose base-3 sum of digits is 3. 10
5, 7, 11, 13, 15, 19, 21, 29, 31, 33, 37, 39, 45, 55, 57, 63, 83, 85, 87, 91, 93, 99, 109, 111, 117, 135, 163, 165, 171, 189, 245, 247, 249, 253, 255, 261, 271, 273, 279, 297, 325, 327, 333, 351, 405, 487, 489, 495, 513, 567, 731, 733, 735, 739, 741, 747, 757 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All of the entries are odd.

Subsequence of A005408. - Michel Marcus, Sep 03 2013

In general, the set of numbers with sum of base-b digits equal to b is a subset of { (b-1)*k + 1; k = 2, 3, 4, ... }. - M. F. Hasler, Dec 23 2016

LINKS

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

FORMULA

a(k^3/6 + k^2 + 5*k/6 + j) = 3^(k+1) + A055235(j-1) for 1 <= j <= k^2/2+5*k/2+2. - Robert Israel, Jun 05 2018

EXAMPLE

The ternary expansion of 5 is (1,2), which has sum of digits 3.

The ternary expansion of 31 is (1,0,0,2), which has sum of digits 3.

10 is not on the list since the ternary expansion of 10 is (1,0,1), which has sum of digits 2 not 3.

MAPLE

N:= 10: # for all terms < 3^(N+1)

[seq(seq(seq(3^a+3^b+3^c, c=0..`if`(b=a, b-1, b)), b = 0..a), a=0..N)]; # Robert Israel, Jun 05 2018

MATHEMATICA

Select[Range@ 757, Total@ IntegerDigits[#, 3] == 3 &] (* Michael De Vlieger, Dec 23 2016 *)

PROG

(Sage) [i for i in [0..1000] if sum(Integer(i).digits(base=3))==3]

(PARI) select( is(n)=sumdigits(n, 3)==3, [1..999]) \\ M. F. Hasler, Dec 23 2016

CROSSREFS

Cf. A018900, A023694, A055235, A187813.

Cf. A226969 (b = 4), A227062 (b = 5), A227080 (b = 6), A227092 (b = 7), A227095 (b = 8), A227238 (b = 9), A052224 (b = 10).

Sequence in context: A280199 A196276 A079498 * A287517 A175100 A270998

Adjacent sequences:  A226633 A226634 A226635 * A226637 A226638 A226639

KEYWORD

nonn,base

AUTHOR

Tom Edgar, Aug 31 2013

STATUS

approved

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Last modified May 27 21:07 EDT 2020. Contains 334671 sequences. (Running on oeis4.)