The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A038077 Number of rooted identity trees with 2-colored nodes. 6
 2, 4, 10, 36, 132, 532, 2222, 9584, 42248, 189776, 864830, 3989656, 18593424, 87413444, 414060796, 1974260912, 9467922870, 45638482068, 221001289714, 1074591477112, 5244497440468, 25681907242416, 126149132242490, 621386729646752, 3068748094479108 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Shifts left and halves under Weigh transform. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..500 N. J. A. Sloane, Transforms FORMULA a(n) = 2 * A005753(n). MAPLE b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,       add(binomial(a(i), j)*b(n-i*j, i-1), j=0..n/i)))     end: a:= n-> `if`(n=1, 2, 2*b((n-1)\$2)): seq(a(n), n=1..40); # Alois P. Heinz, May 20 2013 MATHEMATICA b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, Sum[Binomial[a[i], j]*b[n - i*j, i-1], {j, 0, n/i}]]]; a[n_] := If[n==1, 2, 2*b[n-1, n-1]]; Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Mar 01 2016, after Alois P. Heinz *) CROSSREFS Cf. A004111, A038078, A038079, A038080, A246312. Sequence in context: A103854 A126941 A188495 * A006396 A192502 A243567 Adjacent sequences:  A038074 A038075 A038076 * A038078 A038079 A038080 KEYWORD nonn,eigen AUTHOR Christian G. Bower, Jan 04 1999 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 26 11:40 EST 2020. Contains 332279 sequences. (Running on oeis4.)