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A245749 Number of identity trees with n nodes where the maximal outdegree (branching factor) equals 4. 2
2, 6, 21, 63, 185, 512, 1403, 3750, 9928, 25969, 67462, 174039, 446884, 1142457, 2911078, 7396049, 18746761, 47420345, 119746936, 301941284, 760387426, 1912814031, 4807298905, 12071798139, 30292240853, 75965728619, 190398931985, 476980247827, 1194401725174 (list; graph; refs; listen; history; text; internal format)
OFFSET

11,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 11..1000

FORMULA

a(n) = A116380(n) - A116379(n).

MAPLE

b:= proc(n, i, t, k) option remember; `if`(n=0, 1,

      `if`(i<1, 0, add(binomial(b(i-1$2, k$2), j)*

       b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))

    end:

a:= n-> b(n-1$2, 4$2) -b(n-1$2, 3$2):

seq(a(n), n=11..60);

CROSSREFS

Column k=4 of A244523.

Sequence in context: A088812 A228398 A228394 * A001434 A119098 A294706

Adjacent sequences:  A245746 A245747 A245748 * A245750 A245751 A245752

KEYWORD

nonn

AUTHOR

Joerg Arndt and Alois P. Heinz, Jul 31 2014

STATUS

approved

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Last modified August 6 10:01 EDT 2020. Contains 336245 sequences. (Running on oeis4.)