TY - JOUR TI - Some group actions and Fibonacci numbers AB - The Fibonacci sequence has many interesting properties and studied by many mathematicians. The terms of this sequence appear in nature and is connected with combinatorics and other branches of mathematics. In this paper, we investigate the orbit of a special subgroup of the modular group. TakingTc:=(c2+c+1−cc21−c)∈Γ0(c2), c∈Z, c≠0,Tc:=(c2+c+1−cc21−c)∈Γ0(c2), c∈Z, c≠0,we determined the orbit {Trc(∞):r∈N}.{Tcr(∞):r∈N}. Each rational number of this set is the form Pr(c)/Qr(c),Pr(c)/Qr(c), where Pr(c)Pr(c) and Qr(c)Qr(c) are the polynomials in Z[c]Z[c]. It is shown that Pr(1)Pr(1) and Qr(1)Qr(1) the sum of the coefficients of the polynomials Pr(c)Pr(c) and Qr(c)Qr(c) respectively, are the Fibonacci numbers, where $P_{r}(c)=sum limits_{s=0}^{r}(begin{array}{c}2r-s send{array}) c^{2r-2s}+sum limits_{s=1}^{r}(begin{array}{c}2r-s s-1end{array}) c^{2r-2s+1}$andQr(c)=r∑s=1(2r−ss−1)c2r−2s+2Qr(c)=∑s=1r(2r−ss−1)c2r−2s+2 AU - Şanlı, zeynep DO - 10.31801/cfsuasmas.939096 PY - 2022 JO - Communications Faculty of Sciences University of Ankara Series A1: Mathematics and Statistics VL - 71 IS - 1 SN - 1303-5991 SP - 273 EP - 284 DB - TRDizin UR - http://search/yayin/detay/511698 ER -