Question

Cum se aplica formula termenului general pe sirul 1,5,7,17,31,65,127....

Answer 1

   
[tex]\displaystyle \bf \\ \text{\bf Avem sirul: }\\ 1,~5,~7,~17,~31,~65,~127 \hdots\\ \text{\bf Observam ca:} \\ 7 = 2\times 1 + 5\\ 17 = 2\times 5 + 7\\ 31 = 2\times 7 + 17\\ {\bf s.a.m.d.} \text{\bf Rezulta ca termenul general este: } \\ \boxed{\bf a_n = 2\times a_{n-2} + a_{n-1}}~~~n \geq 3 [/tex]