The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A127258 Irregular triangle read by rows: B(n,k) (n>=1, 0<=k<=n(n-1)/2) is such that SUM B(n,k)*q^(n*(n-1)/2-k) gives the expectation of the number of connected components in a random graph on n labeled vertices where every edge is present with probability q. 2
1, -1, 2, 1, 0, -3, 3, 2, -6, 3, 4, 0, -6, 4, -6, 40, -105, 130, -60, -18, 15, 10, 0, -10, 5, -24, 270, -1350, 3925, -7260, 8712, -6485, 2445, 60, -330, -18, 45, 20, 0, -15, 6, 120, -2016, 15750, -75810, 250950, -603435, 1084104, -1471305, 1502550, -1128820, 589281, -182721 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Row-reversed version of A125210, see A125210 for further details.
LINKS
EXAMPLE
Triangle begins:
1;
-1, 2;
1, 0, -3, 3;
2, -6, 3, 4, 0, -6, 4;
-6, 40, -105, 130, -60, -18, 15, 10, 0, -10, 5;
...
PROG
(PARI) { H=sum(n=0, 6, x^n/(1-q)^(n*(n-1)/2)/n!); B=H*log(H); for(n=1, 6, print(Vec((1-q)^(n*(n-1)/2)*n!*polcoeff(B, n, x)))) }
CROSSREFS
Cf. A125210 (row-reversed version), A125209 (dual version).
Sequence in context: A357734 A228821 A336932 * A154557 A049242 A108887
KEYWORD
sign,tabf
AUTHOR
Max Alekseyev, Jan 09 2007
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 18 18:14 EDT 2024. Contains 373486 sequences. (Running on oeis4.)