This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A052303 Number of asymmetric Greg trees. 8
 1, 1, 0, 0, 0, 0, 1, 4, 12, 42, 137, 452, 1491, 4994, 16831, 57408, 197400, 685008, 2395310, 8437830, 29917709, 106724174, 382807427, 1380058180, 4998370015, 18181067670, 66393725289, 243347195594, 894959868983, 3301849331598, 12217869541117, 45335177297876 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,8 COMMENTS A Greg tree can be described as a tree with 2-colored nodes where only the black nodes are counted and the white nodes are of degree at least 3. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1668 FORMULA G.f.: 1+B(x)-B(x)^2 where B(x) is g.f. of A052301. MAPLE b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,       add(binomial(g(i), j)*b(n-i*j, i-1), j=0..n/i)))     end: g:= n-> `if`(n<1, 0, b(n-1\$2)+b(n, n-1)) : a:= n-> `if`(n=0, 1, g(n)-add(g(j)*g(n-j), j=0..n)): seq(a(n), n=0..40);  # Alois P. Heinz, Jun 22 2018 CROSSREFS Cf. A005263, A005264, A048159, A048160, A052300-A052302. Sequence in context: A237501 A300124 A308371 * A017942 A149344 A178078 Adjacent sequences:  A052300 A052301 A052302 * A052304 A052305 A052306 KEYWORD nonn AUTHOR Christian G. Bower, Nov 15 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 December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)