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A228901 Column 1 of triangle A228900. 1
1, 3, 15, 155, 2685, 65517, 2063205, 79715229, 3653521179, 193876702019, 11696128639195, 790788563411431, 59238930606369007, 4870881096635599567, 436176889680415116607, 42256722956163045301807, 4403938204071514872757477, 491317594015782152377769725, 58423874601431980415156917525 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Triangle A228900 is defined by g.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n^2, (n-k)*k) * y^k ).

LINKS

Table of n, a(n) for n=1..19.

PROG

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

for(n=1, 20, print1(a(n), ", "))

CROSSREFS

Cf. A228900.

Sequence in context: A162078 A245069 A317667 * A195226 A264558 A136519

Adjacent sequences:  A228898 A228899 A228900 * A228902 A228903 A228904

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Sep 07 2013

STATUS

approved

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Last modified June 17 17:46 EDT 2021. Contains 345085 sequences. (Running on oeis4.)