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A319938 O.g.f. A(x) satisfies: [x^n] exp(-n*A(x)) / (1 - n*x) = 0, for n > 0. 6
1, 1, 3, 18, 165, 2019, 30688, 554784, 11591649, 274313325, 7242994143, 210931834662, 6713206636084, 231754182524900, 8624280230971980, 344124280164153056, 14656294893872323449, 663624782214112471329, 31833832291287920426617, 1612762327644980719082470, 86050799297228500838101677, 4823357354919905244973170883, 283375597845431500054861239512 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

It is remarkable that this sequence should consist entirely of integers.

Compare to: [x^n] exp(-n*G(x)) * (1 + n*x) = 0, for n > 0, when G(x) = x - x*G(x)*G'(x), where G(-x)/(-x) is the o.g.f. of A088716.

LINKS

Paul D. Hanna, Table of n, a(n) for n = 1..300

EXAMPLE

O.g.f.: A(x) = x + x^2 + 3*x^3 + 18*x^4 + 165*x^5 + 2019*x^6 + 30688*x^7 + 554784*x^8 + 11591649*x^9 + 274313325*x^10 + ...

ILLUSTRATION OF DEFINITION.

The table of coefficients of x^k/k! in exp(-n*A(x)) / (1 - n*x) begins:

n=1: [1, 0, -1, -16, -423, -19616, -1444625, -154014624, ...];

n=2: [1, 0, 0, -20, -768, -38832, -2895680, -308705280, ...];

n=3: [1, 0, 3, 0, -783, -53568, -4309605, -465802704, ...];

n=4: [1, 0, 8, 56, 0, -50144, -5307200, -616050432, ...];

n=5: [1, 0, 15, 160, 2265, 0, -4729025, -711963600, ...];

n=6: [1, 0, 24, 324, 6912, 145584, 0, -613885824, ...];

n=7: [1, 0, 35, 560, 15057, 460768, 13696795, 0, ...];

n=8: [1, 0, 48, 880, 28032, 1050432, 44437120, 1769051136, 0, ...]; ...

in which the coefficient of x^n in row n forms a diagonal of zeros.

RELATED SERIES.

exp(A(x)) = 1 + x + 3*x^2/2! + 25*x^3/3! + 529*x^4/4! + 22581*x^5/5! + 1598011*x^6/6! + 166508413*x^7/7! + 23765885025*x^8/8! + ...

exp(-A(x)) = 1 - x - x^2/2! - 13*x^3/3! - 359*x^4/4! - 17501*x^5/5! - 1326929*x^6/6! - 143902249*x^7/7! - 21072159247*x^8/8! + ...

PROG

(PARI) {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0); m=#A; A[m] = Vec( exp(-m*x*Ser(A))/(1-m*x +x^2*O(x^m)))[m+1]/m ); A[n]}

for(n=1, 30, print1(a(n), ", "))

CROSSREFS

Cf. A088716, A321085, A319939, A319940, A320417.

Sequence in context: A089466 A302585 A107403 * A053513 A138211 A052668

Adjacent sequences:  A319935 A319936 A319937 * A319939 A319940 A319941

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Oct 09 2018

STATUS

approved

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Last modified July 11 17:24 EDT 2020. Contains 335626 sequences. (Running on oeis4.)