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A000306
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Number of trees of diameter 8.
(Formerly M3552 N1440)
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3
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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
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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9,2
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REFERENCES
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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).
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LINKS
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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