来自在线整数百科全书的问候语!http://oeis.org/ Search: id:a105426 Showing 1-1 of 1 %I A105426 %S A105426 1,5,39,307,2417,19029,149815,1179491,9286113,73109413,575589191, %T A105426 4531604115,35677243729,280886345717,2211413522007,17410421830339, %U A105426 137071961120705,1079165267135301,8496250175961703,66890836140558323 %N A105426 a(0)=1, a(1)=5, a(n)=8*a(n-1)-a(n-2). %C A105426 15*a(n)^2-14 is a square for all n. %H A105426 Tanya Khovanova,递归序列%H A1054常系数线性递归的索引项,签名(8,- 1)。双向无穷序列索引条目%F A1054 26 G.F.:(1-3x)/(1-8x+x^ 2)。A(n)=2×A105045(2×n+1)-1。a(-n)=2*A105045(2*n)-1, if n>0. %F A105426 a(n)=(1/2)*[4-sqrt(15)]^n-(1/30)*[4-sqrt(15)]^n*sqrt(15)+(1/2)*[4+sqrt(15)]^n+(1/30)*sqrt(15) *[4+sqrt(15)]^n, with n>=0 - _Paolo P. Lava_, Jul 08 2008 %t A105426 LinearRecurrence[{8,-1},{1,5},20] (* _Harvey P. Dale_, Feb 25 2016 *) %o A105426 (PARI) a(n)=subst(19*poltchebi(n)-poltchebi(n-1),x,4)/15 %Y A105426 Cf. a(n) = A001090(n+1) - 3*A001090(n). %K A105426 nonn,easy %O A105426 0,2 %A A105426 _Michael Somos_, Apr 10 2005 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE