login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A275421 Triangle read by rows: T(n,k) = number of graphs with n edges and k connected components. 2
1, 1, 1, 3, 1, 1, 5, 4, 1, 1, 12, 8, 4, 1, 1, 30, 23, 9, 4, 1, 1, 79, 57, 26, 9, 4, 1, 1, 227, 160, 68, 27, 9, 4, 1, 1, 710, 456, 197, 71, 27, 9, 4, 1, 1, 2322, 1402, 567, 208, 72, 27, 9, 4, 1, 1, 8071, 4468, 1748, 604, 211, 72, 27, 9, 4, 1, 1, 29503, 15071, 5555, 1874 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Multiset transformation of A002905.

LINKS

Alois P. Heinz, Rows n = 1..60, flattened

Peter Steinbach, Field Guide to Simple Graphs, Volume 4, Table 1.1a, Part 1 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

Index entries for triangles generated by the Multiset Transformation

FORMULA

T(n,1) = A002905(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)^(-A002905(j)). - Alois P. Heinz, Apr 13 2017

EXAMPLE

      1

      1     1

      3     1     1

      5     4     1     1

     12     8     4     1     1

     30    23     9     4     1     1

     79    57    26     9     4     1     1

    227   160    68    27     9     4     1     1

    710   456   197    71    27     9     4     1     1

   2322  1402   567   208    72    27     9     4     1     1

   8071  4468  1748   604   211    72    27     9     4     1     1

  29503 15071  5555  1874   615   212    72    27     9     4     1

CROSSREFS

Cf. A002905 (column 1), A000664 (row sums).

Sequence in context: A131767 A026780 A209421 * A243576 A211314 A026703

Adjacent sequences:  A275418 A275419 A275420 * A275422 A275423 A275424

KEYWORD

nonn,tabl

AUTHOR

R. J. Mathar, Jul 27 2016

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 20 07:01 EST 2018. Contains 299358 sequences. (Running on oeis4.)