A357800 - OEIS

%I #8 Oct 15 2022 10:37:20

%S 1,18,18,14364,58968,14364,70203672,671650056,671650056,70203672,

%T 1192064637456,20707300240704,47530354598496,20707300240704,

%U 1192064637456,52269828456672288,1437626817559769760,5941554215913771840,5941554215913771840,1437626817559769760,52269828456672288,4930307288899134335424,197041019249105562351744,1283341580573615116868160,2308585363008068715943680

%N Coefficients T(n,k) of x^(4*n+1)*r^(4*k)/(4*n+1)! in power series S(x,r) = Integral C(x,r)^3 * D(x,r)^3 dx such that C(x,r)^4 - S(x,r)^4 = 1 and D(x,r)^4 - r^4*S(x,r)^4 = 1, as a symmetric triangle read by rows.

%H Paul D. Hanna, <a href="/A357800/b357800.txt">Table of n, a(n) for n = 0..2925</a>

%F Generating function S(x,r) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(4*n+1) * r^(4*k) / (4*n+1)! and related functions C(x,r) and D(x,r) satisfy the following formulas.

%F For brevity, some formulas here will use S = S(x,r), C = C(x,r), and D = D(x,r).

%F (1.a) C(x,r)^4 - S(x,r)^4 = 1.

%F (1.b) D(x,r)^4 - r^4 * S(x,r)^4 = 1.

%F (1.c) D(x,r)^4 - r^4 * C(x,r)^4 = 1 - r^4.

%F Integral formulas.

%F (2.a) S(x,r) = Integral C(x,r)^3 * D(x,r)^3 dx.

%F (2.b) C(x,r) = 1 + Integral S(x,r)^3 * D(x,r)^3 dx.

%F (2.c) D(x,r) = 1 + r^4 * Integral S(x,r)^3 * C(x,r)^3 dx.

%F (2.d) S(x,r)^4 = Integral 4 * S(x,r)^3 * C(x,r)^3 * D(x,r)^3 dx.

%F Derivatives.

%F (3.a) d/dx S(x,r) = C(x,r)^3 * D(x,r)^3.

%F (3.b) d/dx C(x,r) = S(x,r)^3 * D(x,r)^3.

%F (3.c) d/dx D(x,r) = r^4 * S(x,r)^3 * C(x,r)^3.

%F Exponential formulas.

%F (4.a) C + S = exp( Integral (C^2 - C*S + S^2) * D^3 dx ).

%F (4.b) D + r*S = exp( r * Integral (D^2 - r*D*S + r^2*S^2) * C^3 dx ).

%F (4.c) C - S = exp( -Integral (C^2 + C*S + S^2) * D^3 dx ).

%F (4.d) D - r*S = exp( -r * Integral (D^2 + r*D*S + r^2*S^2) * C^3 dx ).

%F (5.a) C^2 + S^2 = exp( 2 * Integral S*C * D^3 dx ).

%F (5.b) D^2 + r^2*S^2 = exp( 2*r^2 * Integral S*D * C^3 dx ).

%F (5.c) C^2 - S^2 = exp( -2 * Integral S*C * D^3 dx ).

%F (5.d) D^2 - r^2*S^2 = exp( -2*r^2 * Integral S*D * C^3 dx ).

%F Hyperbolic functions.

%F (6.a) C = sqrt(C^2 - S^2) * cosh( Integral (C^2 + S^2) * D^3 dx ).

%F (6.b) S = sqrt(C^2 - S^2) * sinh( Integral (C^2 + S^2) * D^3 dx ).

%F (6.c) D = sqrt(D^2 - r^2*S^2) * cosh( r * Integral (D^2 + r^2*S^2) * C^3 dx ).

%F (6.d) r*S = sqrt(D^2 - r^2*S^2) * sinh( r * Integral (D^2 + r^2*S^2) * C^3 dx ).

%F (7.a) C^2 = cosh( 2 * Integral S*C * D^3 dx ).

%F (7.b) S^2 = sinh( 2 * Integral S*C * D^3 dx ).

%F (7.c) D^2 = cosh( 2*r^2 * Integral S*D * C^3 dx ).

%F (7.d) r^2*S^2 = sinh( 2*r^2 * Integral S*D * C^3 dx ).

%F Other formulas.

%F (8) S(x,r) = Series_Reversion( Integral ( (1 + x^4)^3 * (1 + r^4*x^4)^3 )^(-1/4) dx ).

%F (9.a) T(n,0) = T(n,n) = A153301(n).

%F (9.b) Sum_{k=0..n} T(n,k) = A357804(n), for n >= 0.

%e E.g.f.: S(x,r) = Sum_{n>=0} T(n,k) * x^(4*n+1) * r^(4*k) / (4*n+1)! begins:

%e S(x,r) = x + (18 + 18*r^4)*x^5/5! + (14364 + 58968*r^4 + 14364*r^8)*x^9/9! + (70203672 + 671650056*r^4 + 671650056*r^8 + 70203672*r^12)*x^13/13! + (1192064637456 + 20707300240704*r^4 + 47530354598496*r^8 + 20707300240704*r^12 + 1192064637456*r^16)*x^17/17! + (52269828456672288 + 1437626817559769760*r^4 + 5941554215913771840*r^8 + 5941554215913771840*r^12 + 1437626817559769760*r^16 + 52269828456672288*r^20)*x^21/21! + (4930307288899134335424 + 197041019249105562351744*r^4 + 1283341580573615116868160*r^8 + 2308585363008068715943680*r^12 + 1283341580573615116868160*r^16 + 197041019249105562351744*r^20 + 4930307288899134335424*r^24)*x^25/25! + ...

%e where S(x,r) = Integral C(x,r)^3 * D(x,r)^3 dx.

%e TRIANGLE.

%e This triangle of coefficients T(n,k) of x^(4*n+1) * r^(4*k) / (4*n+1)! in S(x,r) for n >= 0, k = 0..n, begins:

%e n = 0: [1];

%e n = 1: [18, 18];

%e n = 2: [14364, 58968, 14364];

%e n = 3: [70203672, 671650056, 671650056, 70203672];

%e n = 4: [1192064637456, 20707300240704, 47530354598496, 20707300240704, 1192064637456];

%e n = 5: [52269828456672288, 1437626817559769760, 5941554215913771840, 5941554215913771840, 1437626817559769760, 52269828456672288];

%e n = 6: [4930307288899134335424, 197041019249105562351744, 1283341580573615116868160, 2308585363008068715943680, 1283341580573615116868160, 197041019249105562351744, 4930307288899134335424]; ...

%e in which both column 0 and the main diagonal equals A153301.

%e RELATED SERIES.

%e C(x,r) = 1 + 6*x^4/4! + (2268 + 6048*r^4)*x^8/8! + (7434504 + 56282688*r^4 + 35126784*r^8)*x^12/12! + (95227613712 + 1409371197696*r^4 + 2514356038656*r^8 + 679185948672*r^12)*x^16/16! + (3354162536029536 + 81696140755536384*r^4 + 284770675495950336*r^8 + 220415417637617664*r^12 + 33022883487154176*r^16)*x^20/20! + (264444869673131894208 + 9583398717725834749440*r^4 + 54913653475645427527680*r^8 + 83079959422282198548480*r^12 + 35701050229143616880640*r^16 + 3393656235362623684608*r^20)*x^24/24! + ...

%e where C(x,r)^4 - S(x,r)^4 = 1.

%e D(x,r) = 1 + 6*r^4*x^4/4! + (6048*r^4 + 2268*r^8)*x^8/8! + (35126784*r^4 + 56282688*r^8 + 7434504*r^12)*x^12/12! + (679185948672*r^4 + 2514356038656*r^8 + 1409371197696*r^12 + 95227613712*r^16)*x^16/16! + (33022883487154176*r^4 + 220415417637617664*r^8 + 284770675495950336*r^12 + 81696140755536384*r^16 + 3354162536029536*r^20)*x^20/20! + (3393656235362623684608*r^4 + 35701050229143616880640*r^8 + 83079959422282198548480*r^12 + 54913653475645427527680*r^16 + 9583398717725834749440*r^20 + 264444869673131894208*r^24)*x^24/24! +

%e where D(x,r)^4 - r^4 * S(x,r)^4 = 1.

%o (PARI) {T(n, k) = my(S=x, C=1, D=1); for(i=0, n,

%o S = intformal( C^3*D^3 +O(x^(4*n+4)));

%o C = 1 + intformal( S^3*D^3);

%o D = 1 + r^4*intformal( S^3*C^3); );

%o (4*n+1)!*polcoeff( polcoeff(S, 4*n+1, x), 4*k, r)}

%o for(n=0, 10, for(k=0, n, print1( T(n, k), ", ")); print(""))

%o (PARI) /* Using Series Reversion (faster) */

%o {T(n, k) = my(S = serreverse( intformal( 1/((1 + x^4)^3*(1 + r^4*x^4)^3 +O(x^(4*n+4)) )^(1/4) )) );

%o (4*n+1)!*polcoeff( polcoeff(S, 4*n+1, x), 4*k, r)}

%o for(n=0, 10, for(k=0, n, print1( T(n, k), ", ")); print(""))

%Y Cf. A153301 (column 0), A357804 (row sums), A357801 (C(x,r)), A357802 (D(x,r)).

%Y Cf. A357540.

%K nonn,tabl

%O 0,2

%A _Paul D. Hanna_, Oct 14 2022