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A350229
a(n) is the sum of n and the balanced ternary digits in n.
3
0, 2, 2, 4, 6, 4, 6, 8, 8, 10, 12, 12, 14, 16, 12, 14, 16, 16, 18, 20, 20, 22, 24, 22, 24, 26, 26, 28, 30, 30, 32, 34, 32, 34, 36, 36, 38, 40, 40, 42, 44, 38, 40, 42, 42, 44, 46, 46, 48, 50, 48, 50, 52, 52, 54, 56, 56, 58, 60, 58, 60, 62, 62, 64, 66, 66, 68
OFFSET
0,2
COMMENTS
The image of this sequence is the set of nonnegative even numbers (A005843).
FORMULA
a(n) = n + A065363(n).
a(n) = n iff n belongs to A174658.
EXAMPLE
For n = 42:
- the balanced ternary representation of 42 is "1TTT0",
- so a(42) = 42 + 1 - 1 - 1 - 1 + 0 = 40.
MATHEMATICA
Array[# + Total[If[First@ # == 0, Rest@ #, #] &[Prepend[IntegerDigits[#, 3], 0] //. {x___, y_, k_ /; k > 1, z___} :> {x, y + 1, k - 3, z}]] &, 70, 0] (* Michael De Vlieger, Jan 15 2022 *)
PROG
(PARI) a(n) = my (v=n, d); while (n, n=(n-d=[0, 1, -1][1+n%3])/3; v+=d); v
CROSSREFS
See A062028, A092391, A230641 for similar sequences.
Cf. A005843, A065363, A174658 (fixed points).
Sequence in context: A073256 A166362 A050469 * A085730 A232065 A219741
KEYWORD
nonn,base,easy
AUTHOR
Rémy Sigrist, Jan 09 2022
STATUS
approved