cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A152807 G.f.: limit of the ratio of the g.f.s of adjacent rows in triangle A152805.

Original entry on oeis.org

1, 1, 4, 16, 72, 340, 1688, 8648, 45468, 243832, 1328800, 7337500, 40965984, 230864496, 1311526532, 7502799104, 43183861352, 249897858164, 1453076715976, 8485587751112, 49745923115916, 292655237446616, 1727193226708608
Offset: 0

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Author

Paul D. Hanna, Dec 28 2008

Keywords

Comments

Triangle A152805 lists coefficients of a q-analog of the tangent numbers (A000182).
The q-exponential of x is e_q(x,q) = Sum_{n>=0} x^n/faq(n,q) where faq(n,q) = Product_{k=1..n} (q^k-1)/(q-1) is the q-factorial of n. - Paul D. Hanna, Feb 18 2024

Examples

			G.f.: 1 + q + 4*q^2 + 16*q^3 + 72*q^4 + 340*q^5 + 1688*q^6 + 8648*q^7 +...
SAMPLE ROW G.F.s OF TRIANGLE A152805:
R_4(q) = -1 + 3*q + 3*q^2 - 3*q^4 - 3*q^5 + q^6;
R_5(q) = -1 + 4*q + 3*q^2 - 3*q^3 - 4*q^4 - 14*q^5 - 4*q^6 - 3*q^7 +...;
R_6(q) = -1 + 5*q + 2*q^2 - 9*q^3 - 11*q^4 - 19*q^5 - 16*q^6 - 11*q^7 +...
RATIO OF ROW G.F.s approach the g.f. of this sequence:
R_4(q)/R_5(q) = 1 + q + 4*q^2 + 16*q^3 + 72*q^4 + 309*q^5 +...
R_5(q)/R_6(q) = 1 + q + 4*q^2 + 16*q^3 + 72*q^4 + 340*q^5 +...
Limit_{n->infty} R_n(q)/R_{n+1}(q) = 1 + q + 4*q^2 + 16*q^3 + 72*q^4 +...
		

Crossrefs

Programs

  • Mathematica
    (* Calculation of constants {d,c}: *) {1/r, -s*Log[r]*Sqrt[r*Derivative[0, 1][QPochhammer][2*s, r] / (2*Pi*QPolyGamma[1, Log[2*s]/Log[r], r])]} /. FindRoot[{1 + QPochhammer[2*s, r] == 0, Log[1 - r] + QPolyGamma[0, Log[2*s]/Log[r], r] == 0}, {r, 1/6}, {s, 2}, WorkingPrecision -> 70] (* Vaclav Kotesovec, Feb 18 2024 *)
  • PARI
    /* Limit of n-th row polynomial in q of triangle A152805 */
    {faq(n,q) = prod(j=1, n, (q^j-1)/(q-1))} \\ q-factorial of n
    {R(n) = faq(n,q) * polcoeff( 2/(1 + sum(m=0, n, (2*x)^m/faq(m,q) + x*O(x^(n+2)))), n, x)}
    {a(n) = polcoeff(R(n)/R(n+1) + q*O(q^n), n, q)}
    for(n=0,30, print1(a(n),", ")) \\ Paul D. Hanna, Feb 18 2024
    
  • PARI
    /* A(q) satisfies -1 = Product_{n>=0} (1 - 2*q^n*A(q)) */
    {a(n) = my(A=[1]); for(i=1,n, A = concat(A,0);
    A[#A] = polcoeff( 1 + prod(k=0,#A, 1 - 2*x^k*Ser(A))/2, #A-1, x) );A[n+1]}
    for(n=0,30, print1(a(n),", ")) \\ Paul D. Hanna, Feb 18 2024

Formula

From Paul D. Hanna, Feb 18 2024: (Start)
G.f. A(q) = Sum_{n>=0} a(n)*q^n satisfies the following formulas.
(1) A(q) = limit_{n->oo} R_{n}(q) / R_{n+1}(q) where R_{n}(q) = faq(n,q) * [x^n] 2/(1 + e_q(2*x,q)) is the n-th row polynomial in q of triangle A152805, e_q(x,q) is the q-exponential of x and faq(n,q) is the q-factorial of n.
(2) -1 = Product_{n>=0} (1 - 2*q^n*A(q)).
(3) -1 = Sum_{n>=0} (-2)^n * q^(n*(n-1)/2) * A(q)^n / Product_{k=1..n} (1 - q^k).
(End)
From Vaclav Kotesovec, Feb 18 2024: (Start)
Formula (2) can be rewritten as the functional equation QPochhammer(2*y,x) = -1.
a(n) ~ c * d^n / n^(3/2), where d = 6.3144728881807672285224679191139428... and c = 0.461350895847503384343179658336... (End)

A370442 Expansion of g.f. A(q) satisfying -2 = Product_{n>=0} (1 - 3*q^n*A(q)).

Original entry on oeis.org

1, 2, 12, 78, 570, 4434, 36174, 305142, 2640612, 23311068, 209111736, 1900666896, 17466522690, 162014855658, 1514885838582, 14263411673472, 135117683341050, 1286880634334490, 12315286940334942, 118362499698060384, 1141990331203349562, 11056838563337857548, 107394670044059002968
Offset: 0

Views

Author

Paul D. Hanna, Feb 18 2024

Keywords

Examples

			G.f.: A(q) = 1 + 2*q + 12*q^2 + 78*q^3 + 570*q^4 + 4434*q^5 + 36174*q^6 + 305142*q^7 + 2640612*q^8 + 23311068*q^9 + 209111736*q^10 + ...
where A(q) satisfies the infinite product
-2 = (1 - 3*A(q)) * (1 - 3*q*A(q)) * (1 - 3*q^2*A(q)) * (1 - 3*q^3*A(q)) * (1 - 3*q^4*A(q)) * (1 - 3*q^5*A(q)) * ...
		

Crossrefs

Programs

  • Mathematica
    (* Calculation of constants {d,c}: *) With[{m = 3}, {1/r, -s*Log[r] * Sqrt[r*Derivative[0, 1][QPochhammer][m*s, r] / (2*Pi*(m - 1)*QPolyGamma[1, Log[m*s]/Log[r], r])]} /. FindRoot[{m + QPochhammer[m*s, r] == 1, Log[1 - r] + QPolyGamma[0, Log[m*s]/Log[r], r] == 0}, {r, 1/m^2}, {s, 2}, WorkingPrecision -> 70]] (* Vaclav Kotesovec, Feb 18 2024 *)
  • PARI
    /* A(q) satisfies -2 = Product_{n>=0} (1 - 3*q^n*A(q)) */
    {a(n) = my(A=[1]); for(i=1,n, A = concat(A,0);
    A[#A] = polcoeff( 2 + prod(k=0,#A, 1 - 3*x^k*Ser(A)) /3, #A-1, x) ); H=A; A[n+1]}
    for(n=0,30, print1(a(n),", "))
    
  • PARI
    /* limit_{n->oo} R_{n}(q) / R_{n+1}(q) */
    {faq(n,q) = prod(j=1, n, (q^j-1)/(q-1))} \\ q-factorial of n
    {R(n) = faq(n,q) * polcoeff( 3/(1 + 2*sum(m=0, n, (3*x)^m/faq(m,q) + x*O(x^(n+2)))), n, x)}
    {a(n) = polcoeff(R(n+2)/R(n+3) + q*O(q^n), n, q)}
    for(n=0,30, print1(a(n),", "))

Formula

G.f. A(q) = Sum_{n>=0} a(n)*q^n satisfies the following formulas.
(1) -2 = Product_{n>=0} (1 - 3*q^n*A(q)).
(2) -2 = Sum_{n>=0} (-3)^n * q^(n*(n-1)/2) * A(q)^n / Product_{k=1..n} (1 - q^k).
(3) A(q) = lim_{n->oo} R_{n}(q) / R_{n+1}(q) where R_{n}(q) = faq(n,q) * [x^n] 3/(1 + 2*e_q(3*x,q)), e_q(x,q) is the q-exponential of x and faq(n,q) is the q-factorial of n.
a(n) ~ c * d^n / n^(3/2), where d = 10.3914965886269147720490605009350781702243358825286425537327254915874... and c = 0.49970395101356434785108820969954986510927554236884857759717688447784... - Vaclav Kotesovec, Feb 18 2024

A370443 Expansion of g.f. A(q) satisfying -3 = Product_{n>=0} (1 - 4*q^n*A(q)).

Original entry on oeis.org

1, 3, 24, 216, 2184, 23592, 267144, 3128472, 37582680, 460564632, 5735093832, 72359126376, 923021734344, 11884281689688, 154243249784856, 2015831498613720, 26506024201097352, 350404606655241768, 4654501489433893512, 62092356103141330584, 831534637662059617368
Offset: 0

Views

Author

Paul D. Hanna, Feb 18 2024

Keywords

Examples

			G.f.: A(q) = 1 + 3*q + 24*q^2 + 216*q^3 + 2184*q^4 + 23592*q^5 + 267144*q^6 + 3128472*q^7 + 37582680*q^8 + 460564632*q^9 + 5735093832*q^10 + ...
where A(q) satisfies the infinite product
-3 = (1 - 4*A(q)) * (1 - 4*q*A(q)) * (1 - 4*q^2*A(q)) * (1 - 4*q^3*A(q)) * (1 - 4*q^4*A(q)) * (1 - 4*q^5*A(q)) * ...
		

Crossrefs

Programs

  • Mathematica
    (* Calculation of constants {d,c}: *) With[{m = 4}, {1/r, -s*Log[r] * Sqrt[r*Derivative[0, 1][QPochhammer][m*s, r] / (2*Pi*(m - 1)*QPolyGamma[1, Log[m*s]/Log[r], r])]} /. FindRoot[{m + QPochhammer[m*s, r] == 1, Log[1 - r] + QPolyGamma[0, Log[m*s]/Log[r], r] == 0}, {r, 1/m^2}, {s, 2}, WorkingPrecision -> 70]] (* Vaclav Kotesovec, Feb 18 2024 *)
  • PARI
    /* A(q) satisfies -3 = Product_{n>=0} (1 - 4*q^n*A(q)) */
    {a(n) = my(A=[1]); for(i=1,n, A = concat(A,0);
    A[#A] = polcoeff( 3 + prod(k=0,#A, 1 - 4*x^k*Ser(A)) /4, #A-1, x) ); H=A; A[n+1]}
    for(n=0,30, print1(a(n),", "))
    
  • PARI
    /* limit_{n->oo} R_{n}(q) / R_{n+1}(q) */
    {faq(n,q) = prod(j=1, n, (q^j-1)/(q-1))} \\ q-factorial of n
    {R(n) = faq(n,q) * polcoeff( 4/(1 + 3*sum(m=0, n, (4*x)^m/faq(m,q) + x*O(x^(n+2)))), n, x)}
    {a(n) = polcoeff(R(n+1)/R(n+2) + q*O(q^n), n, q)}
    for(n=0,30, print1(a(n),", "))

Formula

G.f. A(q) = Sum_{n>=0} a(n)*q^n satisfies the following formulas.
(1) -3 = Product_{n>=0} (1 - 4*q^n*A(q)).
(2) -3 = Sum_{n>=0} (-4)^n * q^(n*(n-1)/2) * A(q)^n / Product_{k=1..n} (1 - q^k).
(3) A(q) = lim_{n->oo} R_{n}(q) / R_{n+1}(q) where R_{n}(q) = faq(n,q) * [x^n] 4/(1 + 3*e_q(4*x,q)), e_q(x,q) is the q-exponential of x and faq(n,q) is the q-factorial of n.
a(n) ~ c * d^n / n^(3/2), where d = 14.4231123176639449630408542507057843543532473958120624505916750124669... and c = 0.51707658317945675859732872615636765308571079799394608380170536716694... - Vaclav Kotesovec, Feb 18 2024

A370445 Expansion of g.f. A(q) satisfying -5 = Product_{n>=0} (1 - 6*q^n*A(q)).

Original entry on oeis.org

1, 5, 60, 840, 13200, 222060, 3914880, 71382000, 1335069060, 25471344000, 493782003960, 9698680513380, 192596799930360, 3860313616039080, 77994531433117500, 1586781765309289080, 32479537197876474480, 668397905439059302860, 13820909295920888641200, 287010766542642877455600
Offset: 0

Views

Author

Paul D. Hanna, Feb 18 2024

Keywords

Examples

			G.f.: A(q) = 1 + 5*q + 60*q^2 + 840*q^3 + 13200*q^4 + 222060*q^5 + 3914880*q^6 + 71382000*q^7 + 1335069060*q^8 + 25471344000*q^9 + 493782003960*q^10 + ...
where A(q) satisfies the infinite product
-5 = (1 - 6*A(q)) * (1 - 6*q*A(q)) * (1 - 6*q^2*A(q)) * (1 - 6*q^3*A(q)) * (1 - 6*q^4*A(q)) * (1 - 6*q^5*A(q)) * ...
		

Crossrefs

Programs

  • Mathematica
    (* Calculation of constants {d,c}: *) With[{m = 6}, {1/r, -s*Log[r] * Sqrt[r*Derivative[0, 1][QPochhammer][m*s, r] / (2*Pi*(m - 1)*QPolyGamma[1, Log[m*s]/Log[r], r])]} /. FindRoot[{m + QPochhammer[m*s, r] == 1, Log[1 - r] + QPolyGamma[0, Log[m*s]/Log[r], r] == 0}, {r, 1/m^2}, {s, 2}, WorkingPrecision -> 70]] (* Vaclav Kotesovec, Feb 18 2024 *)
  • PARI
    /* A(q) satisfies -5 = Product_{n>=0} (1 - 6*q^n*A(q)) */
    {a(n) = my(A=[1]); for(i=1,n, A = concat(A,0);
    A[#A] = polcoeff( 5 + prod(k=0,#A, 1 - 6*x^k*Ser(A)) /6, #A-1, x) ); H=A; A[n+1]}
    for(n=0,30, print1(a(n),", "))
    
  • PARI
    /* limit_{n->oo} R_{n}(q) / R_{n+1}(q) */
    {faq(n,q) = prod(j=1, n, (q^j-1)/(q-1))} \\ q-factorial of n
    {R(n) = faq(n,q) * polcoeff( 6/(1 + 5*sum(m=0, n, (6*x)^m/faq(m,q) + x*O(x^(n+2)))), n, x)}
    {a(n) = polcoeff(R(n+1)/R(n+2) + q*O(q^n), n, q)}
    for(n=0,30, print1(a(n),", "))

Formula

G.f. A(q) = Sum_{n>=0} a(n)*q^n satisfies the following formulas.
(1) -5 = Product_{n>=0} (1 - 6*q^n*A(q)).
(2) -5 = Sum_{n>=0} (-6)^n * q^(n*(n-1)/2) * A(q)^n / Product_{k=1..n} (1 - q^k).
(3) A(q) = lim_{n->oo} R_{n}(q) / R_{n+1}(q) where R_{n}(q) = faq(n,q) * [x^n] 6/(1 + 5*e_q(6*x,q)), e_q(x,q) is the q-exponential of x and faq(n,q) is the q-factorial of n.
a(n) ~ c * d^n / n^(3/2), where d = 22.4513560224097075964072006016077322187366268210808011681398076264064... and c = 0.53352515179176712675216292204161595268714373520357919375218426836012... - Vaclav Kotesovec, Feb 18 2024
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