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A325293 E.g.f. C(x) + S(x), where C(x*y*z) + S(x*y*z) = exp( Integral Integral Integral C(x*y*z) dx dy dz ) such that C(x)^2 - S(x)^2 = 1. 0
1, 1, 4, 40, 832, 31232, 1914112, 178872320, 24185421824, 4542993268736, 1147507517751296, 379488219034550272, 160693667742004281344, 85499599518969496600576, 56242680517408749713883136, 45103267674508555161314525184, 43556364453823048960903288455168, 50105222938479119498840420930027520, 68000060622146518553982060676576706560, 107938578855000557533262550908184207294464 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..19.

FORMULA

E.g.f. C(x) + S(x), where series C(x) and S(x) are given by

(0.a) C(x) + S(x) = Sum_{n>=0} a(n)*x^n/(n!)^3,

(0.b) C(x) = Sum_{n>=0} a(2*n)*x^(2*n)/(2*n)!^3,

(0.c) S(x) = Sum_{n>=0} a(2*n+1)*x^(2*n+1)/(2*n+1)!^3,

and satisfy the following relations.

(1.a) C(x)^2 - S(x)^2 = 1.

(1.b) C'(x)/S(x) = S'(x)/C(x) =  1/x * Integral 1/x * Integral C(x) dx dx.

(2.a) S(x) = Integral C(x)/x * Integral 1/x * Integral C(x) dx dx dx.

(2.b) C(x) = 1 + Integral S(x)/x * Integral 1/x * Integral C(x) dx dx dx.

(3.a) C(x) + S(x) = exp( Integral 1/x * Integral 1/x * Integral C(x) dx dx dx ).

(3.b) C(x) = cosh( Integral 1/x * Integral 1/x * Integral C(x) dx dx dx ).

(3.c) S(x) = sinh( Integral 1/x * Integral 1/x * Integral C(x) dx dx dx ).

Integration.

(4.a) S(x*y*z) = Integral C(x*y*z) * Integral Integral C(x*y*z) dx dy dz.

(4.b) C(x*y*z) = 1 + Integral S(x*y*z) * Integral Integral C(x*y*z) dx dy dz.

(4.c) S(x*y*z) = Integral C(x*y*z) * Integral Integral C(x*y*z) dz dy dx.

(4.d) C(x*y*z) = 1 + Integral S(x*y*z) * Integral Integral C(x*y*z) dz dy dx.

Exponential.

(5.a) C(x*y*z) + S(x*y*z) = exp( Integral Integral Integral C(x*y*z) dx dy dz ).

(5.b) C(x*y*z) = cosh( Integral Integral Integral C(x*y*z) dx dy dz ).

(5.c) S(x*y*z) = sinh( Integral Integral Integral C(x*y*z) dx dy dz ).

Derivatives.

(6.a) d/dx S(x*y*z) = C(x*y*z) * Integral Integral C(x*y*z) dy dz.

(6.b) d/dx C(x*y*z) = S(x*y*z) * Integral Integral C(x*y*z) dy dz.

(6.c) d/dy S(x*y*z) = C(x*y*z) * Integral Integral C(x*y*z) dx dz.

(6.d) d/dy C(x*y*z) = S(x*y*z) * Integral Integral C(x*y*z) dx dz.

EXAMPLE

E.g.f.: C(x) + S(x) = 1 + x + 4*x^2/2!^3 + 40*x^3/3!^3 + 832*x^4/4!^3 + 31232*x^5/5!^3 + 1914112*x^6/6!^3 + 178872320*x^7/7!^3 + 24185421824*x^8/8!^3 + 4542993268736*x^9/9!^3 + 1147507517751296*x^10/10!^3 + 379488219034550272*x^11/11!^3 + 160693667742004281344*x^12/12!^3 + 85499599518969496600576*x^13/13!^3 + 56242680517408749713883136*x^14/14!^3 + 45103267674508555161314525184*x^15/15!^3 + 43556364453823048960903288455168*x^16/16!^3 + 50105222938479119498840420930027520*x^17/17!^3 + 68000060622146518553982060676576706560*x^18/18!^3 + 107938578855000557533262550908184207294464*x^19/19!^3 + 198840485174399292764682317537473563673493504*x^20/20!^3 + ...

where C(x*y*z) + S(x*y*z) = exp( Integral Integral Integral C(x*y*z) dx dy dz )

such that C(x)^2 - S(x)^2 = 1.

The e.g.f. as a series of reduced fractional coefficients begins

C(x) + S(x) = 1 + x + 1/2*x^2 + 5/27*x^3 + 13/216*x^4 + 61/3375*x^5 + 7477/1458000*x^6 + 8734/6251175*x^7 + 1476161/4000752000*x^8 + 2166268/22785532875*x^9 + 17509575161/729137052000000*x^10 + 22619260492/3790943032078125*x^11 + 153249423734669/104811992950896000000*x^12 + ...

RELATED SERIES.

C(x) = 1 + 4*x^2/2!^3 + 832*x^4/4!^3 + 1914112*x^6/6!^3 + 24185421824*x^8/8!^3 + 1147507517751296*x^10/10!^3 + 160693667742004281344*x^12/12!^3 + 56242680517408749713883136*x^14/14!^3 + 43556364453823048960903288455168*x^16/16!^3 + 68000060622146518553982060676576706560*x^18/18!^3 + 198840485174399292764682317537473563673493504*x^20/20!^3 + ...

where C(x) = cosh( Integral 1/x * Integral 1/x * Integral C(x) dx dx dx ),

also, C(x*y*z) = cosh( Integral Integral Integral C(x*y*z) dx dy dz ).

S(x) = x + 40*x^3/3!^3 + 31232*x^5/5!^3 + 178872320*x^7/7!^3 + 4542993268736*x^9/9!^3 + 379488219034550272*x^11/11!^3 + 85499599518969496600576*x^13/13!^3 + 45103267674508555161314525184*x^15/15!^3 + 50105222938479119498840420930027520*x^17/17!^3 + 107938578855000557533262550908184207294464*x^19/19!^3 + ...

where S(x) = sinh( Integral 1/x * Integral 1/x * Integral C(x) dx dx dx ),

also, S(x*y*z) = sinh( Integral Integral Integral C(x*y*z) dx dy dz ).

PROG

(PARI) {a(n) = my(C=1, S=x); for(i=1, n,

S = intformal( C/x * intformal( 1/x * intformal( C + x*O(x^n))));

C = 1 + intformal( S/x * intformal( 1/x * intformal( C + x*O(x^n)))); );

n!^3 * polcoeff(E = C + S, n)}

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

CROSSREFS

Cf. A325290 (variant).

Sequence in context: A087047 A211035 A053514 * A121276 A013053 A055128

Adjacent sequences:  A325290 A325291 A325292 * A325294 A325295 A325296

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 21 2019

STATUS

approved

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Last modified December 4 22:42 EST 2021. Contains 349526 sequences. (Running on oeis4.)