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.

A107092 G.f. A(x) satisfies A(x)^3 = A(x^3) + 3*x.

Original entry on oeis.org

1, 1, -1, 2, -4, 9, -22, 55, -142, 376, -1011, 2758, -7614, 21220, -59630, 168759, -480533, 1375676, -3957075, 11430582, -33144264, 96434321, -281447954, 823734157, -2417092933, 7109265120, -20955593252, 61893804180, -183148075432, 542885589115, -1611809502764, 4792612539375
Offset: 0

Views

Author

Paul D. Hanna, May 11 2005

Keywords

Comments

Self-convolution cube is A107093.

Examples

			A(x)^3 = 1 + 3*x + x^3 - x^6 + 2*x^9 - 4*x^12 + 9*x^15 - 22*x^18 +...
A(x^3) = 1 + x^3 - x^6 + 2*x^9 - 4*x^12 + 9*x^15 - 22*x^18+...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x);for(i=1,n,A=(subst(A,x,x^3)+3*x+x*O(x^n))^(1/3)); polcoeff(A,n,x)}

A264228 G.f. A(x) satisfies: A(x)^3 = A( x^3/(1-3*x) ), with A(0) = 0.

Original entry on oeis.org

1, 1, 2, 5, 13, 35, 97, 274, 785, 2275, 6656, 19630, 58295, 174175, 523238, 1579584, 4789919, 14584723, 44577799, 136732988, 420784888, 1298937282, 4021383654, 12483820395, 38853994422, 121220646116, 379062880051, 1187912517953, 3730305167438, 11736596024002, 36994041916973, 116807229667919, 369415244627269, 1170113816365089
Offset: 1

Views

Author

Paul D. Hanna, Nov 08 2015

Keywords

Comments

Radius of convergence is r = (sqrt(13) - 3)/2, where r = r^3/(1-3*r), with A(r) = 1.
Compare to a g.f. M(x) of Motzkin numbers: M(x)^2 = M(x^2/(1-2*x)) where M(x) = (1-x - sqrt(1-2*x-3*x^2))/(2*x).

Examples

			G.f.: A(x) = x + x^2 + 2*x^3 + 5*x^4 + 13*x^5 + 35*x^6 + 97*x^7 + 274*x^8 + 785*x^9 + 2275*x^10 + 6656*x^11 + 19630*x^12 + 58295*x^13 + 174175*x^14 + ...
where A(x)^3 = A( x^3/(1-3*x) ).
RELATED SERIES.
A(x)^3 = x^3 + 3*x^4 + 9*x^5 + 28*x^6 + 87*x^7 + 270*x^8 + 839*x^9 + 2610*x^10 + 8127*x^11 + 25331*x^12 + 79035*x^13 + 246852*x^14 + 771808*x^15 + ...
A( x/(1+x+x^2) ) = x + x^4 + 2*x^7 + 6*x^10 + 22*x^13 + 88*x^16 + 367*x^19 + 1570*x^22 + 6843*x^25 + 30271*x^28 + 135530*x^31 + 612852*x^34 + 2794412*x^37 + 12832472*x^40 + ...
Let B(x) = x/Series_Reversion(A(x)), then A(x) = x*B(A(x)), where
B(x) = 1 + x + x^2 + x^3 - x^5 - x^6 + 2*x^8 + 3*x^9 - 6*x^11 - 9*x^12 + 20*x^14 + 30*x^15 - 71*x^17 - 110*x^18 + 267*x^20 + 419*x^21 - 1041*x^23 + ...
Let C0(x) and C2(x) be series trisections of B(x), B(x) = C0(x) + x + C2(x):
C0(x) = 1 + x^3 - x^6 + 3*x^9 - 9*x^12 + 30*x^15 - 110*x^18 + 419*x^21 - 1648*x^24 + 6652*x^27 - 27369*x^30 + 114384*x^33 - 484276*x^36 + ...
C2(x) = x^2 - x^5 + 2*x^8 - 6*x^11 + 20*x^14 - 71*x^17 + 267*x^20 - 1041*x^23 + 4168*x^26 - 17047*x^29 + 70902*x^32 + ... + (-1)^(n-1)*A370446(n)*x^(3*n-1) + ...
then C0(x) = x^2/C2(x).
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=x); for(i=1, n, A = ( subst(A, x, x^3/(1-3*x +x*O(x^n))) )^(1/3) ); polcoeff(A, n)}
    for(n=1, 40, print1(a(n), ", "))

Formula

G.f. A(x) = Sum_{n>=1} a(n)*x^n satisfies the following.
(1) A(x)^3 = A( x^3/(1-3*x) ).
(2) A( x/(1+3*x) )^3 = A( x^3/(1+3*x)^2 ). - Paul D. Hanna, Mar 25 2023
(3) A( x/(1+x+x^2) )^3 = A( x^3/(1-x^3)^2 ). - Paul D. Hanna, Mar 11 2024

A361762 Expansion of g.f. A(x) satisfying A(x)^3 = A( x^3/(1 - 3*x)^3 ) / (1 - 3*x).

Original entry on oeis.org

1, 1, 2, 5, 15, 52, 197, 779, 3135, 12709, 51757, 211761, 871022, 3603282, 14992067, 62719588, 263724900, 1114107925, 4726879206, 20135644606, 86099626270, 369492052236, 1591170063412, 6875211016868, 29803706856996, 129607445296468, 565362988510604, 2473576310166981
Offset: 0

Views

Author

Paul D. Hanna, Mar 23 2023

Keywords

Comments

Related Catalan identity: C(x)^2 = C( x^2/(1 - 2*x)^2 ) / (1 - 2*x), where C(x) = 1 + x*C(x)^2 is the g.f. of the Catalan numbers (A000108).
Radius of convergence of g.f. A(x) is r where r is the real root of r = (1 - 3*r)^(3/2) with A(r) = 1/r^(1/3) = 1.6716998816571609697481497812195572... so that A(r)^3 = A(r)/(1 - 3*r) and r = (52 - (324*sqrt(717) + 8108)^(1/3) + (324*sqrt(717) - 8108)^(1/3))/162 = 0.214054846272632706742187569443388024...

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 5*x^3 + 15*x^4 + 52*x^5 + 197*x^6 + 779*x^7 + 3135*x^8 + 12709*x^9 + 51757*x^10 + 211761*x^11 + 871022*x^12 + ...
such that A(x)^3 = A( x^3/(1 - 3*x)^3 ) / (1 - 3*x).
RELATED SERIES.
A(x)^3 = 1 + 3*x + 9*x^2 + 28*x^3 + 93*x^4 + 333*x^5 + 1271*x^6 + 5064*x^7 + 20673*x^8 + 85460*x^9 + ... + A361763(n+1)*x^n + ...
A( x^3/(1 - 3*x)^3 ) = 1 + x^3 + 9*x^4 + 54*x^5 + 272*x^6 + 1251*x^7 + 5481*x^8 + 23441*x^9 + 99279*x^10 + ...
SPECIFIC VALUES.
A(1/5) = ( 5/2 * A(1/8) )^(1/3) = 1.431256341682946446458148822310720...
A(1/5) = (1 - 3/5)^(-1/3) * (1 - 3/8)^(-1/9) * (1 - 3/125)^(-1/27) * (1 - 3/1815848)^(-1/81) * ...
A(1/6) = ( 2 * A(1/27) )^(1/3) = 1.2765282682430983587479124671832773...
A(1/6) = (1 - 3/6)^(-1/3) * (1 - 3/27)^(-1/9) * (1 - 3/13824)^(-1/27) * (1 - 3/2640087986661)^(-1/81) * ...
A(1/9) = ( 3/2 * A(1/216) )^(1/3) = 1.146494555403917024085906029391966218...
A(1/12) = ( 4/3 * A(1/729) )^(1/3) = 1.101146836396635655557234214350215617...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=1); for(i=1, #binary(n+1), A = ( subst(A, x, x^3/(1 - 3*x +x*O(x^n))^3 )/(1 - 3*x +x*O(x^n)) )^(1/3) ); polcoeff(H=A, n)}
    for(n=0, 30, print1(a(n), ", "))

Formula

G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies:
(1) A(x)^3 = A( x^3/(1 - 3*x)^3 ) / (1 - 3*x).
(2) A(x^3) = A( x/(1 + 3*x) )^3 / (1 + 3*x).
(3) A(x) = Product_{n>=1} 1/(1 - 3/F(n,x))^(1/3^n), where F(1,x) = 1/x, F(m,x) = (F(m-1,x) - 3)^3 for m > 1.

A361765 Expansion of g.f. A(x) satisfying A(x)^5 = A( x^5/(1 - 5*x)^5 ).

Original entry on oeis.org

1, 5, 25, 125, 625, 3126, 15655, 78650, 397625, 2031875, 10553128, 56047040, 306020575, 1723544750, 10015548750, 59871903136, 366244516505, 2278239803025, 14324961668875, 90586470006875, 573925269278169, 3633524853973370, 22949197586894725, 144473478898021750
Offset: 1

Views

Author

Paul D. Hanna, Mar 24 2023

Keywords

Comments

Related Catalan identity: F(x)^2 = F( x^2/(1 - 2*x)^2 ), where F(x) = x*C(x)^2 and C(x) = 1 + x*C(x)^2 is the g.f. of the Catalan numbers (A000108).
Radius of convergence of g.f. A(x) is r where r is the real root of r = (1 - 5*r)^(5/4) with A(r) = 1 and r = 0.1549930338264677513709380922535...

Examples

			G.f.: A(x) = x + 5*x^2 + 25*x^3 + 125*x^4 + 625*x^5 + 3126*x^6 + 15655*x^7 + 78650*x^8 + 397625*x^9 + 2031875*x^10 + 10553128*x^11 + ...
where
A( x^5/(1 - 5*x)^5 ) = x^5 + 25*x^6 + 375*x^7 + 4375*x^8 + 43750*x^9 + 393755*x^10 + 3281500*x^11 + 25788125*x^12 + 193496875*x^13 + ...
which equals A(x)^5.
RELATED SERIES.
Notice that the following fifth root is an integer series
( A(x)/x )^(1/5) = 1 + x + 3*x^2 + 11*x^3 + 44*x^4 + 185*x^5 + 806*x^6 + 3627*x^7 + 16926*x^8 + 82615*x^9 + 425633*x^10 + ... + A361764(n)*x^n + ...
SPECIFIC VALUES.
A(1/7) = A(1/32)^(1/5) = 0.5172818651818402813815396980...
A(1/7) = (1/7) * (1 - 5/7)^(-1) * (1 - 5/32)^(-1/5) * (1 - 5/14348907)^(-1/25) * (1 - 5/14348902^5)^(-1/125) * ...
A(1/8) =  A(1/243)^(1/5) = 0.334722270350398633572525135166...
A(1/8) = (1/8) * (1 - 5/8)^(-1) * (1 - 5/243)^(-1/5) * (1 - 5/763633171168)^(-1/25) * (1 - 5/763633171163^5)^(-1/125) * ...
A(1/10) = A(1/3125)^(1/5) = 0.2000640615121819990127352003599...
A(1/10) = (1/10) * (1 - 5/10)^(-1) * (1 - 5/3125)^(-1/5) * (1 - 5/295646655283200000)^(-1/25) * (1 - 5/295646655283199995^5)^(-1/125) * ...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=x); for(i=1, #binary(n+1), A = ( subst(A, x, x^5/(1 - 5*x +x*O(x^n))^5 ) )^(1/5) ); polcoeff(A, n)}
    for(n=1, 30, print1(a(n), ", "))

Formula

G.f. A(x) = Sum_{n>=1} a(n)*x^n satisfies:
(1) A(x)^5 = A( x^5/(1 - 5*x)^5 ).
(2) A(x^5) = A( x/(1 + 5*x) )^5.
(3) A(x) = x * Product_{n>=0} 1/(1 - 5/F(n,x))^(1/5^n), where F(0,x) = 1/x, F(m,x) = (F(m-1,x) - 5)^5 for m > 0.
Showing 1-4 of 4 results.