cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A322411 Compound tribonacci sequence with a(n) = A278040(A278041(n)), for n >= 0.

Original entry on oeis.org

12, 36, 56, 80, 93, 117, 137, 161, 185, 205, 229, 242, 266, 286, 310, 330, 354, 367, 391, 411, 435, 459, 479, 503, 516, 540, 560, 584, 597, 621, 641, 665, 689, 709, 733, 746, 770, 790, 814, 834, 858, 871, 895, 915, 939, 963, 983, 1007, 1020, 1044, 1064, 1088, 1112, 1132, 1156, 1169, 1193, 1213, 1237, 1257, 1281
Offset: 0

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Author

Wolfdieter Lang, Jan 02 2019

Keywords

Comments

The nine sequences A308199, A319967, A319968, A322410, A322409, A322411, A322413, A322412, A322414 are based on defining the tribonacci ternary word to start with index 0 (in contrast to the usual definition, in A080843 and A092782, which starts with index 1). As a result these nine sequences differ from the compound tribonacci sequences defined in A278040, A278041, and A319966-A319972. - N. J. A. Sloane, Apr 05 2019

Crossrefs

Formula

a(n) = A(C(n)) = A(C(n) + 1) - 2 = 4*A(n) + 3*B(n) + 2*n + 8, for n >= 0, with A = A278040 and C = A278041. For a proof see the W. Lang link in A278040, Proposition 9, eq. (50).
This formula already follows from Theorem 15 in the 1972 paper by Carlitz et al., which gives that b(c(n)) = a(n) + 2b(n) + 2c(n), where a, b and c are the classical positional sequences of the letters in the tribonacci word. The connection is made by using that c(n) = a(n) + b(n) + n, and by making the translation B(n) = a(n+1)-1, A(n) = b(n+1)-1, C(n) = c(n+1)-1. (Note the switching of A and B!). - Michel Dekking, Apr 07 2019
a(n+1) = A319969(n)-1 = A003145(A003146(n))-1, the corresponding classical compound tribonacci sequence. - Michel Dekking, Apr 04 2019

A319971 a(n) = A003146(A003145(n)).

Original entry on oeis.org

11, 35, 55, 79, 92, 116, 136, 160, 184, 204, 228, 241, 265, 285, 309, 329, 353, 366, 390, 410, 434, 458, 478, 502, 515, 539, 559, 583, 596, 620, 640, 664, 688, 708, 732, 745, 769, 789, 813, 833, 857, 870, 894, 914, 938, 962, 982, 1006, 1019, 1043, 1063, 1087
Offset: 1

Views

Author

N. J. A. Sloane, Oct 05 2018

Keywords

Comments

By analogy with the Wythoff compound sequences A003622 etc., the nine compounds of A003144, A003145, A003146 might be called the tribonacci compound sequences. They are A278040, A278041, and A319966-A319972.
This sequence gives the positions of the word cabab in the tribonacci word t = abacabaa..., fixed point of the morphism a->ab, b->ac, c->a. This follows from the fact that the word bab is always preceded in t by the word ca, and the formula CB = BC-2, where A := A003144, B := A003145, C := A003146. See A319969 for BC, the positional sequence of the word bab. - Michel Dekking, Apr 09 2019

Crossrefs

Formula

a(n) = A003146(A003145(n)).
a(n) = 3*A003144(n) + 4*A003145(n) + 2*(n-1) = 4*A278040(n-1) + 3*A278039(A27n-1) + 2*n + 5, n >= 1. For a proof see the W. Lang link in A278040, Proposition 9, eq. (54). Wolfdieter Lang, Apr 11 2019

Extensions

More terms from Rémy Sigrist, Oct 16 2018
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