The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A308189 Numbers of the form t_n or t_n + t_{n+1} where {t_n} are the tribonacci numbers A000073. 1
 0, 1, 2, 3, 4, 6, 7, 11, 13, 20, 24, 37, 44, 68, 81, 125, 149, 230, 274, 423, 504, 778, 927, 1431, 1705, 2632, 3136, 4841, 5768, 8904, 10609, 16377, 19513, 30122, 35890, 55403, 66012, 101902, 121415, 187427, 223317, 344732, 410744, 634061, 755476, 1166220, 1389537, 2145013, 2555757, 3945294, 4700770, 7256527 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Orders of squares in the ternary tribonacci word A080843. This is A213816 with duplicates removed. LINKS Colin Barker, Table of n, a(n) for n = 1..1000 Hamoon Mousavi, Jeffrey Shallit, Mechanical Proofs of Properties of the Tribonacci Word, arXiv:1407.5841 [cs.FL], 2014. H. Mousavi and J. Shallit, Mechanical Proofs of Properties of the Tribonacci Word, In: Manea F., Nowotka D. (eds) Combinatorics on Words. WORDS 2015. Lecture Notes in Computer Science, vol 9304. Springer, 2015, pp. 170-190. Index entries for linear recurrences with constant coefficients, signature (0,1,0,1,0,1). FORMULA From Colin Barker, Jun 11 2019: (Start) G.f.: x^2*(1 + 2*x + 2*x^2 + 2*x^3 + 2*x^4 + x^5 + x^6) / (1 - x^2 - x^4 - x^6). a(n) = a(n-2) + a(n-4) + a(n-6) for n>8. (End) PROG (PARI) concat(0, Vec(x^2*(1 + 2*x + 2*x^2 + 2*x^3 + 2*x^4 + x^5 + x^6) / (1 - x^2 - x^4 - x^6) + O(x^50))) \\ Colin Barker, Jun 11 2019 CROSSREFS Cf. A000073, A001590, A080843, A092782, A213816. Sequence in context: A202113 A113243 A130690 * A074885 A215231 A301512 Adjacent sequences:  A308186 A308187 A308188 * A308190 A308191 A308192 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Jun 09 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 1 16:44 EST 2021. Contains 349430 sequences. (Running on oeis4.)