Search: id:A026569 Results 1-1 of 1 results found. %I A026569 %S A026569 1,1,3,5,13,27,67,153,375,893,2189,5319,13089,32155,79479,196573, %T A026569 487833,1212135,3018355,7525585,18792303,46980373,117589689,294613155, %U A026569 738844719,1854484305,4658460165,11710592711,29458662005,74151824271 %N A026569 a(n)=T(n,n), T given by A026568. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=0. %H A026569 J. W. Layman, The Hankel Transform and Some of its Properties, J. Integer Sequences, 4 (2001), #01.1.5. %F A026569 a(n)=sum{k=0..floor(n/2), binomial(2k, k)binomial(n-k, k)} - Paul Barry (pbarry(AT)wit.ie), Sep 09 2004 %F A026569 G.f.: sqrt[1/((1-x)(1-x-4x^2))]. - Ralf Stephan, Jan 08 2004 %F A026569 n*a(n)=(2*n-1)*a(n-1)+(3*n-3)*a(n-2)-(4*n-6)*a(n-3). - Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 12 2005 %F A026569 a(n)=sum{k=0..n, C(k, n-k)C(2(n-k), n-k)}; - Paul Barry (pbarry(AT)wit.ie), Jul 30 2005 %F A026569 G.f.: 1/(1-x-2x^2/(1-0x-x^2/(1-x-x^2/(1-0x-2x^2/(1-x-x^2/.... (continued fraction). [From Paul Barry (pbarry(AT)wit.ie), Dec 07 2008] %Y A026569 Sequence in context: A141630 A084173 A000631 this_sequence A035082 A005198 A160823 %Y A026569 Adjacent sequences: A026566 A026567 A026568 this_sequence A026570 A026571 A026572 %K A026569 nonn %O A026569 0,3 %A A026569 Clark Kimberling (ck6(AT)evansville.edu) Search completed in 0.001 seconds