A278039 - OEIS

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A278039

The tribonacci representation of a(n) is obtained by appending a 0 to the tribonacci representation of n (cf. A278038).

0, 2, 4, 6, 7, 9, 11, 13, 15, 17, 19, 20, 22, 24, 26, 28, 30, 31, 33, 35, 37, 39, 41, 43, 44, 46, 48, 50, 51, 53, 55, 57, 59, 61, 63, 64, 66, 68, 70, 72, 74, 75, 77, 79, 81, 83, 85, 87, 88, 90, 92, 94, 96, 98, 100, 101, 103, 105, 107, 109, 111, 112, 114, 116, 118, 120, 122, 124, 125, 127, 129, 131, 132, 134, 136

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OFFSET

0,2

COMMENTS

This sequence records the indices for the 0 values of A080843, ordered increasingly. In the W. Lang link a(n) = B(n). - Wolfdieter Lang, Dec 06 2018

Sequence gives the positions of letter a in the tribonacci word generated by a->ab, b->ac, c->a, when given offset 0. - Michel Dekking, Apr 03 2019

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 0..20000

Wolfdieter Lang, The Tribonacci and ABC Representations of Numbers are Equivalent, arXiv:1810.09787v1 [math.NT], 2018.

Bo Tan and Zhi-Ying Wen, Some properties of the Tribonacci sequence, European Journal of Combinatorics, 28 (2007) 1703-1719. See the sequence O_1(n).

FORMULA

a(n) = A003144(n+1) - 1 = Sum_{k=1..n} A276788(k), n >= 0 (an empty sum is 0).

a(n) = 2*n - (A276798(n) - 1), n >= 0. For a proof see the link, Proposition 6 B). - Wolfdieter Lang, Dec 04 2018

EXAMPLE

The tribonacci representation of 7 is 1000 (see A278038), so a(7) has tribonacci representation 10000, which is 13, so a(7) = 13.

CROSSREFS

Cf. A003144, A276798, A278038, A278040, A278041.

Partial sums of A276788.

Sequence in context: A191176 A184585 A287113 * A076521 A206910 A375496

Adjacent sequences: A278036 A278037 A278038 * A278040 A278041 A278042

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Nov 18 2016

STATUS

approved