English

Degree $5$ Fibonacci Sums via the Gelin-Ces\`aro Identity

Combinatorics 2023-10-10 v3

Abstract

Let FkF_k be the kkth Fibonacci number. Let (Gk)kZ(G_k)_{k\in\mathbb Z} be any sequence obeying the recurrence relation of the Fibonacci numbers. We employ the Gerin-Ces\`aro identity and an identity of Brousseau to evaluate the following sums: j=1n(±1)j1Gj5\sum_{j=1}^n{(\pm 1)^{j - 1}G_j^5}, j=1nGj1GjGj+1Gj+2Gj+m\sum_{j = 1}^n {G_{j - 1} G_{j} G_{j + 1} G_{j + 2} G_{j + m} }, j=1n(Fm3)nj(Fm+2)jGj1GjGj+1Gj+2Gj+m\sum_{j = 1}^n {(-F_{m - 3})^{n - j} ( F_{m + 2} )^j G_{j - 1} G_{j} G_{j + 1} G_{j + 2} G_{j + m} }, and j=1n(Fm+2)n2Fm3jGj+m(Gj2Gj1GjGj+1Gj+2Gj+3)1\sum_{j = 1}^n {(-F_{m + 2})^{n - 2}F_{m - 3}^jG_{j + m} \left( {G_{j - 2} G_{j - 1} G_j G_{j + 1} G_{j + 2} G_{j + 3} } \right)^{ - 1} }. Among other results, we evaluate the sum and alternating sum of products of five consectutive Fibonacci-like numbers, namely j=1n(±1)j1GjGj+1Gj+2Gj+3Gj+4\sum_{j = 1}^n {\left( { \pm 1} \right)^{j - 1} G_j G_{j + 1} G_{j + 2} G_{j + 3} G_{j + 4} }.

Keywords

Cite

@article{arxiv.2309.13074,
  title  = {Degree $5$ Fibonacci Sums via the Gelin-Ces\`aro Identity},
  author = {Kunle Adegoke},
  journal= {arXiv preprint arXiv:2309.13074},
  year   = {2023}
}

Comments

11 pages, no figures or tables