This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A026380 #12 Nov 27 2018 09:29:58 %S A026380 1,3,4,11,17,45,75,195,339,873,1558,3989,7247,18483,34016,86515, %T A026380 160795,408105,764388,1936881,3650571,9238023,17501619,44241261, %U A026380 84179877,212601015,406020930,1024642875,1963073865,4950790605 %N A026380 a(n) = T(n,[ n/2 ]), where T is the array in A026374. %H A026380 D. E. Davenport, L. W. Shapiro and L. C. Woodson, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v18i2p33">The Double Riordan Group</a>, The Electronic Journal of Combinatorics, 18(2) (2012), #P33. - From _N. J. A. Sloane_, May 11 2012 %F A026380 a(2n)=A026378(n+1), a(2n-1)=A026375(n). - _Emeric Deutsch_, Feb 18 2004 %F A026380 a(2n) = A026378(2n+1), a(2n+1) = A026375(n+1). %F A026380 Davenport et al. give a g.f. %Y A026380 Cf. A026375, A026378. %K A026380 nonn %O A026380 0,2 %A A026380 _Clark Kimberling_