A000306 Number of trees of diameter 8. (Formerly M3552 N1440)

1, 4, 19, 66, 219, 645, 1813, 4802, 12265, 30198, 72396, 169231, 387707, 871989, 1930868, 4215615, 9091410, 19389327, 40944999, 85691893, 177898521, 366614456, 750494796, 1526979694, 3089556090, 6219191608, 12460307373, 24856533408, 49387348955, 97765283686, 192870793594, 379287172272

Offset

9,2

References

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Christian Sievers, Table of n, a(n) for n = 9..4442

J. Riordan, Enumeration of trees by height and diameter, IBM J. Res. Dev. 4 (1960), 473-478.

Index entries for sequences related to trees

Prog

(PARI)
sh_euler(p)={my(m=serprec(p, x)-1); x*exp(sum(i=1, m, subst(p+O(x^(1+m\i)), x, x^i)/i))}
lista(n)={my(s2=sh_euler(sh_euler(x+O(x*x^n))), s3=sh_euler(s2), s4=sh_euler(s3), r3=s3-s2, r4=s4-s3, t8=r4-r3*s3); Vec(t8)} \\ Christian Sievers, May 18 2023

Crossrefs

Cf. A034853.

Sequence in context: A098813 A212039 A055485 * A100185 A357251 A291888

Adjacent sequences: A000303 A000304 A000305 * A000307 A000308 A000309

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Christian Sievers, May 18 2023

Status

approved