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A305143 O.g.f. A(x) satisfies: 0 = [x^n] exp( n^2 * Integral A(x)^4 dx ) / A(x), for n > 0. 13
1, 1, 13, 316, 10667, 447576, 22094626, 1242995118, 78081518451, 5400194995057, 406998451178896, 33165909456647704, 2904055577822356346, 271843880829531635092, 27087966494039897011884, 2862718283883222686998584, 319838550858171357010036323, 37670084296166551957561304631 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

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

Note: 0 = [x^n] exp( n * Integral F(x)^4 dx ) / F(x) holds for n > 0 when F(x) = 1 + x*F(x)^5 is a g.f. of A002294.

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..250

FORMULA

(a(n)/n!)^(1/n) tends to 25/4. - Vaclav Kotesovec, Oct 19 2020

EXAMPLE

O.g.f.: A(x) = 1 + x + 13*x^2 + 316*x^3 + 10667*x^4 + 447576*x^5 + 22094626*x^6 + 1242995118*x^7 + 78081518451*x^8 + 5400194995057*x^9 + ...

ILLUSTRATION OF DEFINITION.

The table of coefficients of x^k in exp(n^2*Integral A(x)^4 dx)/A(x) begins:

n=0: [1, -1, -12, -291, -9904, -419430, -20878908, ...];

n=1: [1, 0, -21/2, -284, -78945/8, -420765, -336068285/16, ...];

n=2: [1, 3, 0, -235, -9540, -421722, -21319776, ...];

n=3: [1, 8, 75/2, 0, -61985/8, -408126, -345111453/16, ...];

n=4: [1, 15, 132, 861, 0, -328662, -20947980, ...];

n=5: [1, 24, 651/2, 3384, 226143/8, 0, -268775133/16], ...];

n=6: [1, 35, 672, 9621, 117020, 1187142, 0, ...];

n=7: [1, 48, 2475/2, 23180, 2891295/8, 5049117, 960763011/16, 0, ...]; ...

in which the main diagonal is all zeros after the initial term, illustrating that 0 = [x^n] exp(n^2*Integral A(x)^4 dx)/A(x), for n > 0.

RELATED SERIES.

A(x)^2 = 1 + 2*x + 27*x^2 + 658*x^3 + 22135*x^4 + 924702*x^5 + 45461602*x^6 + 2548558008*x^7 + 159620140335*x^8 + ...

A(x)^3 = 1 + 3*x + 42*x^2 + 1027*x^3 + 34443*x^4 + 1432833*x^5 + 70159774*x^6 + 3919323204*x^7 + 244746587643*x^8 + ...

A(x)^4 = 1 + 4*x + 58*x^2 + 1424*x^3 + 47631*x^4 + 1973476*x^5 + 96250266*x^6 + 5358025992*x^7 + 333596305267*x^8 + ...

exp( Integral A(x)^4 dx) = 1 + x + 9*x^2/2! + 373*x^3/3! + 35809*x^4/4! + 5918961*x^5/5! + 1461206521*x^6/6! + 496585571749*x^7/7! + 220438988917953*x^8/8! + ...

A'(x)/A(x) = 1 + 25*x + 910*x^2 + 41117*x^3 + 2166366*x^4 + 128865058*x^5 + 8487954042*x^6 + 611163126189*x^7 + 47668752953875*x^8 + ...

PROG

(PARI) {a(n) = my(A=[1], m); for(i=1, n+1, m=#A; A=concat(A, 0); A[m+1] = Vec( exp(m^2*intformal(Ser(A)^4)) / Ser(A) )[m+1] ); A[n+1]}

for(n=0, 20, print1(a(n), ", "))

CROSSREFS

Cf. A305137, A305138, A305139, A305140, A305142.

Sequence in context: A331647 A331644 A052114 * A132485 A297437 A166743

Adjacent sequences:  A305140 A305141 A305142 * A305144 A305145 A305146

KEYWORD

nonn

AUTHOR

Paul D. Hanna, May 31 2018

STATUS

approved

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Last modified July 29 12:47 EDT 2021. Contains 346346 sequences. (Running on oeis4.)