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A308199 The tribonacci representation of a(n) is obtained by appending 0,0 to the tribonacci representation of n (cf. A278038). 8

%I #17 Jul 20 2022 08:52:31

%S 0,4,7,11,13,17,20,24,28,31,35,37,41,44,48,51,55,57,61,64,68,72,75,79,

%T 81,85,88,92,94,98,101,105,109,112,116,118,122,125,129,132,136,138,

%U 142,145,149,153,156,160,162,166,169,173,177,180,184,186,190,193,197,200,204,206,210,213,217,221,224,228

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

%C From _Michel Dekking_, Oct 06 2019: (Start)

%C If w is a binary vector not containing 111, then w00 and w01 are also binary vectors not containing 111. So a(n) = A278040(n) - 1.

%C This sequence gives the positions of the word ab in the tribonacci word t, when t is given offset 0.

%C This sequence is the compound sequence A278039(A278039) of the three sequences A278039, A278040, A278041, which are the building blocks of the tribonacci world with offset 0. (End)

%F From _Michel Dekking_, Oct 06 2019: (Start)

%F a(n) = Sum_{k=1..n-1} d(k), where d is the tribonacci word on the alphabet {4,3,2}.

%F a(n) = A003144(A003144(n)) - 1. (End)

%e u = abacabaabacaba.., then u(0)u(1) = ab, u(4)u(5) = ab, u(7)u(8) = ab, u(11)u(12) = ab.

%Y Cf. A278038, A278039, A278040, A278041, A308200.

%Y Essentially partial sums of A276789.

%K nonn,base

%O 0,2

%A _N. J. A. Sloane_, Jun 23 2019

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Last modified March 29 02:15 EDT 2024. Contains 371264 sequences. (Running on oeis4.)