0,4

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

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

D. G. Cantor, personal communication.

E. N. Gilbert, Enumeration of labeled graphs, Canad. J. Math., 8 (1956), 405-411.

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 518.

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 7.

R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.1.

H. S. Wilf, Generatingfunctionology, Academic Press, NY, 1990, p. 78.

T. D. Noe, Table of n, a(n) for n=0..50

Huantian Cao, AutoGF: An Automated System to Calculate Coefficients of Generating Functions.

N. J. A. Sloane, Transforms

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

H. S. Wilf, Generatingfunctionology, 2nd edn., Academic Press, NY, 1994, p. 87, Eq. 3.10.2.

P. Flajolet and R. Sedgewick, Analytic Combinatorics, 2009; see page 138

n*2^binomial(n, 2) = Sum_k binomial(n, k)*k*a(k)*2^binomial(n-k, 2).

E.g.f.: 1+log( sum(2^binomial(n, 2)*x^n/n!, n=0..infinity) ).

t1 := 1+log( add(2^binomial(n, 2)*x^n/n!, n=0..30)): t2 := series(t1, x, 30): A001187 := n->n!*coeff(t2, x, n);

(PARI) a(n)=n!*polcoeff(1+log(sum(k=0, n, 2^binomial(k, 2)*x^k/k!, x*O(x^n))), n)

Logarithmic transform of A006125 (labeled graphs). Cf. A053549.

Row sums of triangle A062734.

Sequence in context: A084284 A084285 A084286 this_sequence A093377 A131591 A030259

Adjacent sequences: A001184 A001185 A001186 this_sequence A001188 A001189 A001190

nonn,nice,easy

N. J. A. Sloane (njas(AT)research.att.com).