login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A207137 G.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n^2, k*(n-k))*x^k ). 5
1, 1, 2, 4, 17, 171, 3171, 101741, 7181615, 1274607729, 428568152553, 223160743256395, 185627109707405932, 320952534083059792786, 1367454166673309618606950, 11078799748881429582280609036, 137939599816546528357634500253053, 2679390013936303204526656964298150849 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The logarithmic derivative yields A207138.

Equals the antidiagonal sums of triangle A228900.

LINKS

Table of n, a(n) for n=0..17.

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 4*x^3 + 17*x^4 + 171*x^5 + 3171*x^6 +...

where the logarithm of the g.f. equals the l.g.f. of A207138:

log(A(x)) = x + 3*x^2/2 + 7*x^3/3 + 51*x^4/4 + 761*x^5/5 + 17913*x^6/6 +...

PROG

(PARI) {a(n)=polcoeff(exp(sum(m=1, n, x^m/m*sum(k=0, m, binomial(m^2, k*(m-k))*x^k))+x*O(x^n)), n)}

for(n=0, 25, print1(a(n), ", "))

CROSSREFS

Cf. A207138 (log), A207135, A228900, A206850, A206830, A167006.

Sequence in context: A247260 A048872 A063800 * A143674 A136147 A275837

Adjacent sequences:  A207134 A207135 A207136 * A207138 A207139 A207140

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Feb 15 2012

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 January 20 23:20 EST 2020. Contains 331104 sequences. (Running on oeis4.)