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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A006202 Number of colorings of labeled graphs on n nodes using exactly 4 colors, divided by 4!*2^6.
(Formerly M5356)
6
0, 0, 0, 1, 80, 7040, 878080, 169967616, 53247344640, 27580935700480, 23884321532149760, 34771166607668412416, 85316631064301031915520, 353171748158258855521812480, 2467057266045387831319241687040, 29078599995993904385498084987109376 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Equals 1/1536*A224068. - Peter Bala, Apr 12 2013

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 18, col. 4 of Table 1.5.1 (divided by 64).

R. C. Read, personal communication.

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

LINKS

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

R. C. Read, The number of k-colored graphs on labelled nodes, Canad. J. Math., 12 (1960), 410—414.

R. C. Read, Letter to N. J. A. Sloane, Oct. 29, 1976

MATHEMATICA

maxn = 16;

t[_, 1] = 1; t[n_, k_] := t[n, k] = Sum[Binomial[n, j]*2^(j*(n - j))*t[j, k - 1]/k, {j, 1, n - 1}];

a[n_] := t[n, 4]/64;

Array[a, maxn]

PROG

(PARI) seq(n)={Vec(serconvol(sum(j=1, n, x^j*j!*2^binomial(j, 2)) + O(x*x^n), (sum(j=1, n, x^j/(j!*2^binomial(j, 2))) + O(x*x^n))^4)/1536, -n)} \\ Andrew Howroyd, Nov 30 2018

CROSSREFS

A diagonal of A058875.

Cf. A000683, A224068.

Sequence in context: A283102 A259076 A190931 * A278736 A116252 A159734

Adjacent sequences:  A006199 A006200 A006201 * A006203 A006204 A006205

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 5 22:37 EST 2019. Contains 329782 sequences. (Running on oeis4.)