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.

A060280 Number of orbits of length n under the map whose periodic points are counted by A001350.

Original entry on oeis.org

1, 0, 1, 1, 2, 2, 4, 5, 8, 11, 18, 25, 40, 58, 90, 135, 210, 316, 492, 750, 1164, 1791, 2786, 4305, 6710, 10420, 16264, 25350, 39650, 61967, 97108, 152145, 238818, 374955, 589520, 927200, 1459960, 2299854, 3626200, 5720274, 9030450, 14263078, 22542396
Offset: 1

Views

Author

Thomas Ward, Mar 29 2001

Keywords

Comments

Euler transform is A000045. 1/((1-x)*(1-x^3)*(1-x^4)*(1-x^5)^2*(1-x^6)^2*...) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 5*x^5 + 8*x^6 + ... - Michael Somos, Jan 28 2003

Examples

			a(7)=4 since the 7th term of A001350 is 29 and the 1st is 1, so there are (29-1)/7 = 4 orbits of length 7.
x + x^3 + x^4 + 2*x^5 + 2*x^6 + 4*x^7 + 5*x^8 + 8*x^9 + 11*x^10 + 18*x^11 + ...
		

Crossrefs

First column of A348422.

Programs

  • Magma
    A060280:= func< n | n le 2 select 2-n else (&+[Lucas(d)*MoebiusMu(Floor(n/d)) : d in Divisors(n)])/n >;
    [A060280(n): n in [1..50]]; // G. C. Greubel, Nov 06 2024
    
  • Maple
    A060280 := proc(n)
        add( numtheory[mobius](d)*A001350(n/d), d=numtheory[divisors](n)) ;
        %/n;
    end proc: # R. J. Mathar, Jul 15 2016
  • Mathematica
    A001350[n_] := LucasL[n] - (-1)^n - 1;
    a[n_] := (1/n)*DivisorSum[n, MoebiusMu[#]*A001350[n/#]& ];
    Array[a, 50] (* Jean-François Alcover, Nov 23 2017 *)
  • PARI
    {a(n) = if( n<3, n==1, sumdiv( n, d, moebius(n/d) * (fibonacci(d - 1) + fibonacci(d + 1))) / n)} /* Michael Somos, Jan 28 2003 */
    
  • SageMath
    A000032=BinaryRecurrenceSequence(1,1,2,1)
    def A060280(n): return sum(A000032(k)*moebius(n/k) for k in (1..n) if (k).divides(n))//n - int(n==2)
    [A060280(n) for n in range(1,41)] # G. C. Greubel, Nov 06 2024

Formula

a(n) = (1/n)* Sum_{d|n} mu(d)*A001350(n/d).
a(n) = A006206(n) except for n=2. - Michael Somos, Jan 28 2003
a(n) = A031367(n)/n. - R. J. Mathar, Jul 15 2016
G.f.: Sum_{k>=1} mu(k)*log(1 + x^k/(1 - x^k - x^(2*k)))/k. - Ilya Gutkovskiy, May 18 2019

A324487 a(n) = A001350(n)^3.

Original entry on oeis.org

0, 1, 1, 64, 125, 1331, 4096, 24389, 91125, 438976, 1771561, 7880599, 32768000, 141420761, 594823321, 2537716544, 10720765125, 45537538411, 192699928576, 817138135549, 3460080078125, 14662949322176, 62103840598801, 263115950765039, 1114512556032000, 4721424167332081, 19999831641819121
Offset: 0

Views

Author

N. J. A. Sloane, Mar 12 2019

Keywords

Crossrefs

Formula

From Colin Barker, Mar 13 2019: (Start)
G.f.: x*(1 + x^2)*(1 - 3*x + 47*x^2 - 96*x^3 + 104*x^4 + 96*x^5 + 47*x^6 + 3*x^7 + x^8) / ((1 - x)*(1 + x)*(1 - 3*x + x^2)*(1 + x - x^2)*(1 - x - x^2)*(1 + 3*x + x^2)*(1 - 4*x - x^2)).
a(n) = 4*a(n-1) + 12*a(n-2) - 44*a(n-3) - 44*a(n-4) + 132*a(n-5) + 66*a(n-6) - 132*a(n-7) - 44*a(n-8) + 44*a(n-9) + 12*a(n-10) - 4*a(n-11) - a(n-12) for n>11. (End)

A324485 a(n) = A324484(n)/n.

Original entry on oeis.org

1, 0, 5, 6, 24, 40, 120, 250, 640, 1452, 3600, 8510, 20880, 50460, 124024, 303750, 750120, 1853120, 4600200, 11437548, 28527320, 71281800, 178526880, 447893250, 1125750120, 2833844040, 7144449920, 18036271740, 45591631800, 115381449692, 292329067800, 741410192250
Offset: 1

Views

Author

N. J. A. Sloane, Mar 12 2019

Keywords

Crossrefs

Programs

  • PARI
    a001350(n) = fibonacci(n+1)+fibonacci(n-1)-1-(-1)^n;
    a(n) = sumdiv(n, d, moebius(n/d)*a001350(d)^2)/n; \\ Seiichi Manyama, Apr 29 2021
    
  • PARI
    f(x) = ((1-x-x^2)*(1+x-x^2))^2/((1-3*x+x^2)*(1-x)^2*(1+x)^4);
    my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, moebius(k)*log(f(x^k))/k)) \\ Seiichi Manyama, Apr 29 2021

Formula

From Seiichi Manyama, Apr 29 2021: (Start)
a(n) = (1/n) * Sum_{d|n} mu(n/d) * A001350(d)^2 = (1/n) * Sum_{d|n} mu(n/d) * A152152(d).
G.f.: Sum_{k>=1} mu(k) * log(f(x^k))/k , where f(x) = ((1-x-x^2) * (1+x-x^2))^2/((1-3*x+x^2) * (1-x)^2 * (1+x)^4). (End)

Extensions

More terms from Seiichi Manyama, Apr 29 2021

A324488 Inflation orbit counts b^{(3)}_n for Danzer's F-type tiling and other 3D cut and project patterns with tau-inflation.

Original entry on oeis.org

1, 0, 63, 124, 1330, 4032, 24388, 91000, 438912, 1770230, 7880598, 32763780, 141420760, 594798932, 2537715150, 10720674000, 45537538410, 192699485568, 817138135548, 3460078306440, 14662949297724, 62103832718202, 263115950765038, 1114512523173000, 4721424167330750
Offset: 1

Views

Author

N. J. A. Sloane, Mar 12 2019

Keywords

Crossrefs

Programs

  • PARI
    a001350(n) = fibonacci(n+1)+fibonacci(n-1)-1-(-1)^n;
    a(n) = sumdiv(n, d, moebius(n/d)*a001350(d)^3); \\ Seiichi Manyama, Apr 29 2021

Formula

a(n) = Sum_{d|n} mu(n/d) * A001350(d)^3 = Sum_{d|n} mu(n/d) * A324487(d). - Seiichi Manyama, Apr 29 2021

Extensions

More terms from Seiichi Manyama, Apr 29 2021
Showing 1-4 of 4 results.