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A275420 Triangle read by rows: T(n,k) = number of regular graphs with n nodes and k connected components. 1
1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 3, 2, 1, 1, 5, 5, 4, 2, 1, 1, 4, 9, 6, 4, 2, 1, 1, 17, 14, 12, 7, 4, 2, 1, 1, 22, 30, 19, 13, 7, 4, 2, 1, 1, 167, 56, 42, 22, 14, 7, 4, 2, 1, 1, 539, 224, 74, 47, 23, 14, 7, 4, 2, 1, 1, 18979, 785, 271, 87, 50, 24, 14, 7, 4, 2, 1, 1, 389436, 19783 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

Multiset transformation of A005177.

LINKS

Table of n, a(n) for n=1..80.

Index entries for triangles generated by the Multiset Transformation

FORMULA

T(n,1) = A005177(n).

T(n,k) = Sum_{c_i*N_i=n,i=1..k} binomial(T(N_i,1)+c_i-1,c_i) for 1<k<=n.

G.f.: Product_{j>=1} (1-y*x^j)^(-A005177(j)). - Alois P. Heinz, Apr 13 2017

EXAMPLE

      1

      1   1

      1   1   1

      2   2   1   1

      2   3   2   1   1

      5   5   4   2   1   1

      4   9   6   4   2   1   1

     17  14  12   7   4   2   1   1

     22  30  19  13   7   4   2   1   1

    167  56  42  22  14   7   4   2   1   1

    539 224  74  47  23  14   7   4   2   1   1

  18979 785 271  87  50  24  14   7   4   2   1   1

CROSSREFS

Cf. A005177 (1st column), A165647 (row sums).

Sequence in context: A011847 A091325 A193596 * A143974 A301565 A237265

Adjacent sequences:  A275417 A275418 A275419 * A275421 A275422 A275423

KEYWORD

nonn,tabl

AUTHOR

R. J. Mathar, Jul 27 2016

STATUS

approved

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Last modified December 18 20:06 EST 2018. Contains 318245 sequences. (Running on oeis4.)