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 1-9 of 9 results.

A203800 a(n) = (1/n) * Sum_{d|n} moebius(n/d) * Lucas(d)^(d-1), where Lucas(n) = A000032(n).

Original entry on oeis.org

1, 1, 5, 85, 2928, 314925, 84974760, 63327890015, 123670531939440, 644385861467631972, 8853970669063185618000, 321538767413685546538468385, 30768712746239178236068160093280, 7755868453482819803691622493685140880, 5144106193113274410507722020733942141881664
Offset: 1

Views

Author

Paul D. Hanna, Jan 06 2012

Keywords

Examples

			G.f.: F(x) = 1/((1-x-x^2) * (1-3*x^2+x^4) * (1-4*x^3-x^6)^5 * (1-7*x^4+x^8)^85 * (1-11*x^5-x^10)^2928 * (1-18*x^6+x^12)^314925 * (1-29*x^7-x^14)^84974760 * (1-47*x^8+x^16)^63327890015 * (1-76*x^9-x^18)^123670531939440 *...).
where F(x) = exp( Sum_{n>=1} Lucas(n)^n * x^n/n ) = g.f. of A156216:
F(x) = 1 + x + 5*x^2 + 26*x^3 + 634*x^4 + 32928*x^5 + 5704263*x^6 +...
so that the logarithm of F(x) begins:
log(F(x)) = x + 3^2*x^2/2 + 4^3*x^3/3 + 7^4*x^4/4 + 11^5*x^5/5 + 18^6*x^6/6 + 29^7*x^7/7 + 47^8*x^8/8 + 76^9*x^9/9 + 123^10*x^10/10 +...+ Lucas(n)^n*x^n +...
		

Crossrefs

Programs

  • Mathematica
    a[n_] := 1/n DivisorSum[n, MoebiusMu[n/#] LucasL[#]^(#-1)&]; Array[a, 15] (* Jean-François Alcover, Dec 23 2015 *)
  • PARI
    {a(n)=if(n<1, 0, sumdiv(n, d, moebius(n/d)*(fibonacci(d-1)+fibonacci(d+1))^(d-1))/n)}
    
  • PARI
    {Lucas(n)=fibonacci(n-1)+fibonacci(n+1)}
    {a(n)=local(F=exp(sum(m=1, n, Lucas(m)^m*x^m/m)+x*O(x^n)));if(n==1,1,polcoeff(F*prod(k=1,n-1,(1 - Lucas(k)*x^k + (-1)^k*x^(2*k) +x*O(x^n))^a(k)),n)/Lucas(n))}

Formula

G.f.: 1/Product_{n>=1} (1 - Lucas(n)*x^n + (-1)^n*x^(2*n))^a(n) = exp(Sum_{n>=1} Lucas(n)^n * x^n/n), which is the g.f. of A156216.
G.f.: Product_{n>=1} G_n(x^n)^a(n) = exp(Sum_{n>=1} Lucas(n)^n * x^n/n) where G_n(x^n) = Product_{k=0..n-1} G(u^k*x) where G(x) = 1/(1-x-x^2) and u is an n-th root of unity.

A067961 Number of binary arrangements without adjacent 1's on n X n torus connected n-s.

Original entry on oeis.org

1, 9, 64, 2401, 161051, 34012224, 17249876309, 23811286661761, 84590643846578176, 792594609605189126649, 19381341794579313317802199, 1242425797286480951825250390016, 208396491430277954192889648311785961, 91534759488004239323168528670973468727049
Offset: 1

Views

Author

R. H. Hardin, Feb 02 2002

Keywords

Examples

			Neighbors for n=4:
| | | |
o o o o
| | | |
| | | |
o o o o
| | | |
| | | |
o o o o
| | | |
| | | |
o o o o
| | | |
		

Crossrefs

Cf. circle A000204, line A000045, arrays: ne-sw nw-se A067965, e-w ne-sw nw-se A067963, n-s nw-se A067964, e-w n-s nw-se A066864, e-w ne-sw n-s nw-se A063443, n-s A067966, e-w n-s A006506, nw-se A067962, toruses: bare A002416, ne-sw nw-se A067960, ne-sw n-s nw-se A067959, e-w ne-sw n-s nw-se A067958, e-w n-s A027683, e-w ne-sw n-s A066866.
Cf. A156216. - Paul D. Hanna, Sep 13 2010
Cf. A215941.

Programs

  • Magma
    [Lucas(n)^n: n in [1..15]]; // Vincenzo Librandi, Mar 15 2014
  • Maple
    a:= n-> (<<0|1>, <1|1>>^n. <<2, 1>>)[1$2]^n:
    seq(a(n), n=1..15);  # Alois P. Heinz, Aug 01 2021
  • Mathematica
    Table[LucasL[n]^n,{n,15}] (* Harvey P. Dale, Mar 13 2014 *)

Formula

a(n) = L(n)^n, where L(n) = A000032(n) is the n-th Lucas number.
Logarithmic derivative of A156216. - Paul D. Hanna, Sep 13 2010
Sum_{n>=1} 1/a(n) = A215941. - Amiram Eldar, Nov 17 2020

Extensions

Edited by Dean Hickerson, Feb 15 2002

A166168 G.f.: exp( Sum_{n>=1} Lucas(n^2)*x^n/n ) where Lucas(n) = A000204(n).

Original entry on oeis.org

1, 1, 4, 29, 585, 34212, 5600397, 2490542953, 2968152042068, 9416588994339205, 79216509536543420965, 1762508872870620792746360, 103525263562786817866762466405, 16031370626878431551103688398524485
Offset: 0

Views

Author

Paul D. Hanna, Oct 08 2009

Keywords

Comments

Conjectured to consist entirely of integers.
The Lucas numbers (A000204) forms the logarithmic derivative of the Fibonacci numbers (A000045).
Note that Lucas(n^2) = [(1+sqrt(5))/2]^(n^2) + [(1-sqrt(5))/2]^(n^2).

Examples

			G.f.: A(x) = 1 + x + 4*x^2 + 29*x^3 + 585*x^4 + 34212*x^5 +...
log(A(x)) = x + 7*x^2/2 + 76*x^3/3 + 2207*x^4/4 + 167761*x^5/5 + 33385282*x^6/6 +...+ Lucas(n^2)*x^n/n +...
		

Crossrefs

Programs

  • Maple
    with(combinat): seq(coeff(series(exp(add((fibonacci(k^2-1)+fibonacci(k^2+1))*x^k/k,k=1..n)),x,n+1), x, n), n = 0 .. 15); # Muniru A Asiru, Dec 18 2018
  • Mathematica
    CoefficientList[Series[Exp[Sum[LucasL[n^2]*x^n/n, {n, 1, 200}]], {x, 0, 50}], x](* G. C. Greubel, May 06 2016 *)
  • PARI
    {a(n)=polcoeff(exp(sum(m=1,n,(fibonacci(m^2-1)+fibonacci(m^2+1))*x^m/m)+x*O(x^n)),n)}

Formula

a(n) = (1/n)*Sum_{k=1..n} Lucas(k^2)*a(n-k), a(0)=1.
Logarithmic derivative yields A166169.

A207834 G.f.: exp( Sum_{n>=1} 5*L(n)*x^n/n ), where L(n) = Fibonacci(n-1)^n + Fibonacci(n+1)^n.

Original entry on oeis.org

1, 5, 25, 130, 1295, 38861, 4227075, 1309117220, 1123176929475, 2564594183278115, 15604715134340991949, 251021373648740285348860, 10668788238489683954523431475, 1195322752666989652479885363067075, 352750492054485236937115646128341734205
Offset: 0

Views

Author

Paul D. Hanna, Feb 20 2012

Keywords

Comments

Given g.f. A(x), note that A(x)^(1/5) is not an integer series.
Compare the definition to the g.f. of the Fibonacci numbers:
1/(1-x-x^2) = exp( Sum_{n>=1} Lucas(n)*x^n/n ), where Lucas(n) = Fibonacci(n-1) + Fibonacci(n+1).

Examples

			G.f.: A(x) = 1 + 5*x + 25*x^2 + 130*x^3 + 1295*x^4 + 38861*x^5 +...
such that, by definition,
log(A(x))/5 = x + 5*x^2/2 + 28*x^3/3 + 641*x^4/4 + 33011*x^5/5 +...+ (Fibonacci(n-1)^n + Fibonacci(n+1)^n)*x^n/n +...
		

Crossrefs

Programs

  • PARI
    {L(n)=fibonacci(n-1)^n+fibonacci(n+1)^n}
    {a(n)=polcoeff(exp(sum(m=1,n,5*L(m)*x^m/m)+x*O(x^n)),n)}
    for(n=0,51,print1(a(n),", "))

A207835 G.f.: exp( Sum_{n>=1} 5*L(n)*x^n/n ), where L(n) = Fibonacci((n-1)^2) + Fibonacci((n+1)^2).

Original entry on oeis.org

1, 15, 200, 3525, 134355, 16781664, 6730280105, 7679335074975, 23795707614699850, 197148338964056588955, 4337960355881995023988299, 252594793852565664429620014530, 38838042059493582778244565420563025, 15744729667082405326504405819215652913325
Offset: 0

Views

Author

Paul D. Hanna, Feb 20 2012

Keywords

Comments

Given g.f. A(x), note that A(x)^(1/5) is not an integer series.
Compare the definition to the g.f. of the Fibonacci numbers:
1/(1-x-x^2) = exp( Sum_{n>=1} Lucas(n)*x^n/n ), where Lucas(n) = Fibonacci(n-1) + Fibonacci(n+1).

Examples

			G.f.: A(x) = 1 + 15*x + 200*x^2 + 3525*x^3 + 134355*x^4 + 16781664*x^5 +...
such that, by definition,
log(A(x))/5 = 3*x + 35*x^2/2 + 990*x^3/3 + 75059*x^4/4 + 14931339*x^5/5 + 7778817074*x^6/6 +...+ (Fibonacci((n-1)^2) + Fibonacci((n+1)^2))*x^n/n +...
		

Crossrefs

Programs

  • PARI
    {L(n)=fibonacci((n-1)^2)+fibonacci((n+1)^2)}
    {a(n)=polcoeff(exp(sum(m=1,n,5*L(m)*x^m/m)+x*O(x^n)),n)}
    for(n=0,21,print1(a(n),", "))

A171186 G.f.: exp( Sum_{n>=1} (x^n/n)*[Sum_{k=0..[n/2]} A034807(n,k)^n] ), where A034807 is a triangle of Lucas polynomials.

Original entry on oeis.org

1, 1, 3, 12, 82, 1350, 97888, 15395388, 3754569984, 3038160817708, 10054063262475469, 52672088781183258841, 474423679267205966998406, 20987531454245723696517676183, 2606758801245041424971290635855234
Offset: 0

Views

Author

Paul D. Hanna, Dec 13 2009

Keywords

Examples

			G.f.: A(x) = 1 + x + 3*x^2 + 12*x^3 + 82*x^4 + 1350*x^5 +...
log(A(x)) = x + 5*x^2/2 + 28*x^3/3 + 273*x^4/4 + 6251*x^5/5 +...+ A171187(n)*x^n/n +...
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(exp(sum(m=1,n,(x^m/m)*sum(k=0, m\2, (binomial(m-k, k)+binomial(m-k-1, k-1))^m))+x*O(x^n)),n)}

A163189 G.f.: A(x) = exp( Sum_{n>=1} (1 + A000204(n)*x)^n * x^n/n ).

Original entry on oeis.org

1, 1, 2, 5, 14, 40, 159, 812, 5133, 42942, 474619, 6708142, 121367878, 2819170132, 83571532538, 3148951107867, 151069353323782, 9219463980803329, 714951048370178409, 70448496563603216429, 8818161368662624534857
Offset: 0

Views

Author

Paul D. Hanna, Jul 22 2009

Keywords

Comments

Compare to g.f. of Fibonacci sequence: exp( Sum_{n>=1} A000204(n)*x^n/n ), where A000204 is the Lucas numbers.

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 5*x^3 + 14*x^4 + 40*x^5 + 159*x^6 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(exp(sum(m=1, n+1, (1+(fibonacci(m-1)+fibonacci(m+1))*x+x*O(x^n))^m*x^m/m)), n)}

A353050 G.f. A(x) satisfies: 0 = Sum_{n>=1} (Lucas(n) - A(x))^n * x^n/n, where Lucas(n) = A000204(n).

Original entry on oeis.org

1, 2, 5, 298, 18949, 3962150, 1916564344, 2501114025582, 8336852053702202, 73027618049882652700, 1666798946804859125492899, 99738726494828465657124210156, 15634873312495144092899303952245929, 6430416165010536428917103922818349814504
Offset: 0

Views

Author

Paul D. Hanna, Apr 26 2022

Keywords

Comments

It is conjectured that this is an integer sequence.
This sequence is a special case of a more general conjecture: 0 = Sum_{n>=1} (L(n) - F(x))^n * x^n/n is satisfied by an integer series F(x) if exp( Sum_{n>=1} L(n) * x^n/n ) yields an integer series.

Examples

			G.f.: A(x) = 1 + 2*x + 5*x^2 + 298*x^3 + 18949*x^4 + 3962150*x^5 + 1916564344*x^6 + 2501114025582*x^7 + 8336852053702202*x^8 + ...
where
0 = (1 - A(x))*x + (3 - A(x))^2*x^2/2 + (4 - A(x))^3*x^3/3 + (7 - A(x))^4*x^4/4 + (11 - A(x))^5*x^5/5 + (18 - A(x))^6*x^6/6 + (29 - A(x))^7*x^7/7 + (47 - A(x))^8*x^8/8 + (76 - A(x))^9*x^9/9 + ... + (Lucas(n) - A(x))^n*x^n/n + ...
Related series.
exp( Sum_{n>=1} A(x)^n * x^n/n ) = 1/(1 - x*A(x)) = 1 + x + 3*x^2 + 10*x^3 + 319*x^4 + 19601*x^5 + 4002282*x^6 + 1924629400*x^7 + 2504975492897*x^8 + 8341867813691252*x^9 + ...
exp( Sum_{n>=1} Lucas(n)^n * x^n/n ) = 1 + x + 5*x^2 + 26*x^3 + 634*x^4 + 32928*x^5 + 5704263*x^6 + 2470113915*x^7 + 2978904483553*x^8 + 9401949327631932*x^9 + ... + A156216(n)*x^n + ...
		

Crossrefs

Programs

  • PARI
    {Lucas(n) = fibonacci(n-1) + fibonacci(n+1)}
    {a(n) = my(A=[1]); for(i=1,n, A=concat(A,0);
    A[#A] = polcoeff( sum(m=1,#A, (Lucas(m) - Ser(A))^m*x^m/m), #A));A[n+1]}
    for(n=0,20,print1(a(n),", "))

A381422 Expansion of g.f. = exp( Sum_{n>=1} A066802(n)*x^n/n ).

Original entry on oeis.org

1, 20, 662, 26780, 1205961, 58050204, 2924165436, 152231599628, 8125577046740, 442293253888592, 24457749066666142, 1370114821790970340, 77591333270514869230, 4434803157977731784808, 255492958449660158603448, 14820943641891118200315756, 864962304943085638764540396
Offset: 0

Views

Author

Karol A. Penson, Apr 22 2025

Keywords

Crossrefs

Formula

G.f. = 64/((1 + sqrt(1 - 4*x^(1/3)))^2*(1 + sqrt(1 + 4*(-1)^(1/3)*x^(1/3)))^2*(1 + sqrt(1 - 4*(-1)^(2/3)*x^(1/3)))^2).
The above g.f. denoted by h satisfies algebraic equation of order eight:
1 + (8*x - 1)*h + 4*x*(7*x + 3)*h^2 + 7*x^2*(8*x - 1)*h^3 + x^2*(70*x^2 - 40*x + 1)*h^4 + 7*x^4*(8*x - 1)*h^5 + 4*x^5*(7*x + 3)*h^6 + x^6*(8*x - 1)*h^7 + x^8*h^8 = 0.
Showing 1-9 of 9 results.