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.

Previous Showing 11-20 of 33 results. Next

A194159 Constant associated with the product of the first n nonzero even-indexed Fibonacci numbers.

Original entry on oeis.org

8, 3, 2, 8, 8, 3, 2, 4, 4, 0, 3, 3, 9, 1, 2, 9, 8, 2, 4, 5, 0, 2, 5, 6, 6, 4, 3, 1, 3, 6, 1, 4, 2, 2, 9, 4, 2, 2, 7, 3, 2, 1, 5, 1, 9, 9, 4, 0, 9, 0, 5, 0, 3, 2, 4, 5, 1, 5, 4, 2, 2, 4, 0, 8, 9, 2, 5, 7, 6, 0, 6, 4, 8, 3, 9, 8, 5, 4, 5, 9, 9, 3, 4, 0, 8, 9, 1, 1, 6, 9, 2, 5, 6, 6, 8, 0, 5, 5, 8, 1, 8, 2, 1, 4, 9, 5, 1, 3
Offset: 0

Views

Author

Johannes W. Meijer, Aug 21 2011

Keywords

Comments

a(n) = Product_{i=1..n} F(2*i) is asymptotic to C2*phi^(n*(n+1))/sqrt(5)^n where phi = (1+sqrt(5))/2 and F(n) = A000045(n), see A194157. The decimal expansion of the constant C2 is given above.

Examples

			C2 = 0.83288324403391298245025664...
		

References

  • Ronald L. Graham, Donald E. Knuth and Oren Patashnik, Concrete Mathematics, 6th printing with corrections. Addison-Wesley, Reading, MA, p. 478 and p. 571, 1990.

Crossrefs

Programs

  • Mathematica
    digits = 108; NProduct[1 - GoldenRatio^(-4*k), {k, 1, Infinity}, WorkingPrecision -> digits+10, NProductFactors -> 200] // RealDigits[#, 10, digits]& // First (* Jean-François Alcover, Feb 14 2013, from 1st formula *)
    RealDigits[QPochhammer[1/GoldenRatio^4], 10, 100][[1]] (* Vladimir Reshetnikov, Sep 15 2016 *)

Formula

Equals Product_{k>=1} (1-alpha^(2*k)) with alpha = -1/phi^2 and phi = (1+sqrt(5))/2.
Equals Sum_{n>=0} (-1)^binomial(n+1,2)*alpha^A152749(n).

A218490 Decimal expansion of Lucas factorial constant.

Original entry on oeis.org

1, 3, 5, 7, 8, 7, 8, 4, 0, 7, 6, 1, 2, 1, 0, 5, 7, 0, 1, 3, 8, 7, 4, 3, 9, 7, 0, 9, 7, 6, 0, 6, 0, 7, 1, 8, 5, 5, 7, 8, 6, 0, 5, 8, 6, 5, 2, 9, 5, 6, 7, 8, 7, 0, 4, 4, 9, 6, 8, 7, 8, 2, 5, 4, 3, 8, 4, 0, 7, 1, 9, 1, 1, 0, 3, 4, 8, 6, 2, 3, 3, 6, 8, 7, 7, 1, 4
Offset: 1

Views

Author

Vaclav Kotesovec, Oct 30 2012

Keywords

Comments

The Lucas factorial constant is associated with the Lucas factorial A135407.

Examples

			1.35787840761210570138743970976060718557860586529567870449687825438407191103...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[QPochhammer[-1, -1/GoldenRatio^2], 10, 105][[1]] (* slightly modified by Robert G. Wilson v, Dec 21 2017 *)
  • PARI
    prodinf(j=0, 1 + ((sqrt(5) - 3)/2)^j) \\ Iain Fox, Dec 21 2017

Formula

Equals exp( Sum_{k>=1} 1/(k*(((3-sqrt(5))/2)^k-(-1)^k)) ). - Vaclav Kotesovec, Jun 08 2013
Equals Product_{k=0..infinity} (1 + (-1)^k/phi^(2*k)). - G. C. Greubel, Dec 23 2017
Equals lim_{n->oo} A135407(n)/phi^(n*(n+1)/2), where phi is the golden ratio (A001622). - Amiram Eldar, Jan 23 2022

A276987 Decimal expansion of (phi-1)_inf = (1/phi)_inf, where (q)_inf is the q-Pochhammer symbol, phi = (1+sqrt(5))/2 is the golden ratio.

Original entry on oeis.org

1, 2, 0, 8, 0, 1, 9, 2, 1, 8, 6, 1, 7, 0, 6, 1, 2, 9, 4, 2, 3, 7, 2, 3, 1, 5, 6, 9, 8, 8, 7, 9, 2, 0, 5, 6, 3, 0, 4, 3, 9, 9, 2, 5, 1, 6, 7, 9, 4, 0, 6, 9, 1, 3, 6, 6, 9, 7, 9, 2, 1, 5, 6, 9, 6, 2, 0, 8, 1, 0, 2, 1, 2, 3, 5, 7, 9, 0, 2, 4, 8, 8, 8, 7, 3, 9, 5, 1, 8, 4, 5, 5, 1, 1, 7, 8, 9, 7, 5, 2
Offset: 0

Views

Author

Vladimir Reshetnikov, Sep 24 2016

Keywords

Comments

(1/phi)_inf appears as a coefficient in asymptotics of A274983, A274985.

Examples

			0.1208019218617061294237231569887920563...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[QPochhammer[1/GoldenRatio], 10, 100][[1]]

Formula

(1/phi)inf = Product{k > 0} (1 - 1/phi^k).

A003268 Central Fibonomial coefficients.

Original entry on oeis.org

1, 2, 6, 15, 60, 260, 1820, 12376, 136136, 1514513, 27261234, 488605194, 14169550626, 411591708660, 19344810307020, 908637119420910, 69056421075989160, 5249543573067466872, 645693859487298425256, 79413089729752455762384, 15803204856220738696714416
Offset: 0

Views

Author

Keywords

References

  • A. Brousseau, Fibonacci and Related Number Theoretic Tables. Fibonacci Association, San Jose, CA, 1972, p. 74.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Central column of A010048, |A055870|.
Cf. A062073.

Programs

  • Mathematica
    Table[Product[Fibonacci[k],{k,Floor[n/2]+1,n}] / Product[Fibonacci[k],{k,1,Ceiling[n/2]}],{n,2,20}] (* Vaclav Kotesovec, Apr 10 2015 *)

Formula

a(n) = (Product_{k=floor(n/2)+1..n} Fibonacci(k)) / (Product_{k=1..ceiling(n/2)} Fibonacci(k)).
a(n) ~ ((1+sqrt(5))/2)^(n^2/4 + n + 1 - (1-(-1)^n)/8) / A062073, where A062073 = 1.2267420107203532444176302... is the Fibonacci factorial constant. - Vaclav Kotesovec, May 01 2015

Extensions

More terms from Vaclav Kotesovec, May 01 2015

A176343 a(n) = Fibonacci(n)*a(n-1) + 1, a(0) = 0.

Original entry on oeis.org

0, 1, 2, 5, 16, 81, 649, 8438, 177199, 6024767, 331362186, 29491234555, 4246737775921, 989489901789594, 373037692974676939, 227552992714552932791, 224594803809263744664718, 358677901683394200229554647, 926823697949890613393169207849
Offset: 0

Views

Author

Roger L. Bagula, Apr 15 2010

Keywords

Crossrefs

Programs

  • GAP
    a:= function(n)
        if n=0 then return 0;
        else return 1 + Fibonacci(n)*a(n-1);
        fi; end;
    List([0..20], n-> a(n) ); # G. C. Greubel, Dec 07 2019
  • Magma
    function a(n)
      if n eq 0 then return 0;
      else return 1 + Fibonacci(n)*a(n-1);
      end if; return a; end function;
    [a(n): n in [0..20]]; // G. C. Greubel, Dec 07 2019
    
  • Maple
    with(combinat);
    a:= proc(n) option remember;
          if n=0 then 0
        else 1 + fibonacci(n)*a(n-1)
          fi; end:
    seq( a(n), n=0..20); # G. C. Greubel, Dec 07 2019
  • Mathematica
    a[n_]:= a[n]= If[n==0, 0, Fibonacci[n]*a[n-1] +1]; Table[a[n], {n,0,20}]
  • PARI
    a(n) = if(n==0, 0, 1 + fibonacci(n)*a(n-1) ); \\ G. C. Greubel, Dec 07 2019
    
  • Sage
    def a(n):
        if (n==0): return 0
        else: return 1 + fibonacci(n)*a(n-1)
    [a(n) for n in (0..20)] # G. C. Greubel, Dec 07 2019
    

Formula

a(n) = Fibonacci(n)*a(n-1) + 1, a(0) = 0.
a(n) ~ c * ((1+sqrt(5))/2)^(n^2/2+n/2) / 5^(n/2), where c = A062073 * A101689 = 3.317727324507285486862890025085971028467... is product of Fibonacci factorial constant (see A062073) and Sum_{n>=1} 1/(Product_{k=1..n} A000045(k) ). - Vaclav Kotesovec, Feb 20 2014

A194160 Constant associated with the product of the first n nonzero odd-indexed Fibonacci numbers.

Original entry on oeis.org

1, 4, 7, 2, 8, 8, 5, 9, 2, 9, 0, 9, 9, 5, 6, 9, 3, 1, 4, 6, 0, 7, 1, 3, 4, 2, 8, 1, 5, 0, 3, 8, 1, 5, 9, 3, 2, 2, 6, 9, 6, 2, 9, 5, 1, 5, 2, 6, 5, 6, 9, 9, 0, 5, 3, 7, 1, 1, 1, 5, 8, 6, 2, 3, 7, 6, 2, 7, 3, 6, 4, 9, 2, 8, 7, 7, 0, 5, 3, 7, 4, 4, 8, 2, 0, 5, 3, 1, 5, 9, 0, 6, 0, 9, 3, 6, 0
Offset: 1

Views

Author

Johannes W. Meijer, Aug 21 2011

Keywords

Comments

A194158(n) = prod(i=1..n, F(2*i-1) ) is asymptotic to C1*phi^(n*n)/sqrt(5)^n where phi=(1+sqrt(5))/2 and F(n) = A000045(n). The decimal expansion of the constant C1 is given here.

Examples

			C1 = 1.4728859290995693146071...
		

References

  • Ronald L. Graham, Donald E. Knuth and Oren Patashnik, Concrete Mathematics, 6th printing with corrections. Addison-Wesley, Reading, MA, p. 478 and p. 571, 1990.

Crossrefs

Programs

  • Mathematica
    RealDigits[Product[1-((-1)/GoldenRatio^2)^(2k-1),{k,1000}],10, 100] [[1]] (* Harvey P. Dale, Aug 28 2011 *)
    RealDigits[QPochhammer[-GoldenRatio^2, 1/GoldenRatio^4]/(GoldenRatio Sqrt[5]), 10, 100][[1]] (* Vladimir Reshetnikov, Sep 15 2016 *)

Formula

C1 = prod(k>=1, 1-alpha^(2*k-1) ) where alpha = (-1/phi^2) and phi = (1+sqrt(5))/2.

A256831 Decimal expansion of Pell factorial constant.

Original entry on oeis.org

1, 1, 4, 1, 9, 8, 2, 5, 6, 9, 6, 6, 7, 7, 9, 1, 2, 0, 6, 0, 2, 8, 0, 4, 3, 3, 3, 8, 3, 6, 7, 8, 6, 0, 1, 5, 0, 8, 6, 4, 7, 3, 0, 4, 8, 2, 4, 0, 8, 5, 4, 0, 7, 9, 1, 5, 5, 6, 2, 5, 4, 3, 5, 2, 4, 4, 9, 8, 4, 3, 7, 8, 5, 4, 8, 0, 6, 2, 0, 8, 6, 0, 7, 8, 2, 5, 0, 6, 3, 7, 0, 6, 0, 9, 2, 5, 3, 3, 4, 7, 8, 1, 6, 3, 6
Offset: 1

Views

Author

Vaclav Kotesovec, Apr 10 2015

Keywords

Examples

			1.141982569667791206028043338367860150864730482408540791556...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[N[QPochhammer[2*Sqrt[2]-3], 105]][[1]]

Formula

Equals limit n->infinity A256832(n) / ((1+sqrt(2))^(n*(n+1)/2) / 2^(3*n/2)).

A181926 Diagonal sums of Fibonomial triangle A010048.

Original entry on oeis.org

1, 1, 2, 2, 4, 6, 13, 27, 70, 191, 609, 2130, 8526, 38156, 194000, 1109673, 7176149, 52238676, 429004471, 3970438003, 41454181730, 488046132076, 6482590679282, 97134793638750, 1641654359781521, 31285014253070731, 672372121341768918, 16299021330860540657
Offset: 0

Views

Author

Emanuele Munarini, Apr 02 2012

Keywords

Comments

Cf. A000045 (Fibonacci) as diagonal sums of A007318 (Pascal's Triangle). For Fibonacci numbers, the ratio A000045(i+1)/A000045(i) approaches the golden ratio (1+sqrt(5))/2 as i increases. For this sequence, it appears that (a(i+5)/a(i+4))/(a(i+1)/a(i)) approaches the golden ratio. - Dale Gerdemann, Apr 23 2015
This sequence can be interpreted as counting colored, square-domino tilings of a 1xn board, where the number of colors available for a domino with k squares to the left is Fib(k+1) and the number of colors available for a square with k dominoes to the left is Fib(k-1). "Fib(n)" here is A000045 (Fibonacci), extended so that Fib(-1) = 1, Fib(0) = 0,... . As an example, let d be a domino, s be a square an consider the uncolored tilings of length 5: sssss, sssd, ssds, sdss, dsss, sdd, dsd, dds. Then, after each 's' or 'd', write the number of colors available: s1s1s1s1s1, s1s1s1d3, s1s1d2s0, s1d1s0s0, d1s0s0s0, s1d1d1, d1s0d1, d1d1s1. So the number of colorings for these tilings is: 1,3,0,0,0,1,0,1 and the total number of colored tilings is 6 (= a(5)). - Dale Gerdemann, Apr 30 2015

Crossrefs

Programs

  • Mathematica
    Table[Sum[Product[Fibonacci[k-j+1]/Fibonacci[j],{j,1,n-k}],{k,Ceiling[n/2],n}],{n,0,30}] (* Vaclav Kotesovec, Apr 29 2015 *)
    (* Or, since version 10 *) Table[Sum[Fibonorial[k]/Fibonorial[2k-n]/Fibonorial[n-k],{k,Ceiling[n/2],n}],{n,0,30}] (* Vaclav Kotesovec, Apr 30 2015 *)
    (* List of the multiplicative constants from an asymptotic formula: *) {N[EllipticTheta[3, 0, GoldenRatio^(-2)]/QPochhammer[-(GoldenRatio^2)^(-1)], 80], N[Sum[GoldenRatio^(-2*(j + 1/4)^2), {j, -Infinity, Infinity}]/QPochhammer[-(GoldenRatio^2)^(-1)], 80], N[EllipticTheta[2, 0, GoldenRatio^(-2)]/QPochhammer[-(GoldenRatio^2)^(-1)], 80]} (* Vaclav Kotesovec, Apr 30 2015 *)
  • Maxima
    ffib(n):=prod(fib(k),k,1,n);
    fibonomial(n,k):=ffib(n)/(ffib(k)*ffib(n-k));
    makelist(sum(fibonomial(k,n-k),k,ceiling(n/2),n),n,0,30);

Formula

a(n) = sum(fibonomial(k,n-k),k=ceiling(n/2)..n).
From Vaclav Kotesovec, Apr 29 2015: (Start)
a(n) ~ c * ((1+sqrt(5))/2)^(n^2/8), where
c = 1.472885929099569314607134281503815932269629515265... if mod(n,4)=0,
c = 1.472782295338429619549807628338486893461428897618... if mod(n,4)=1 or 3,
c = 1.472678661577289942545896597162143392952724631588... if mod(n,4)=2.
Or c = Sum_{j} ((1+sqrt(5))/2)^(-2*(j+(1-cos(Pi*n/2))/4)^2) / A062073, where A062073 = 1.2267420107203532444176302... is the Fibonacci factorial constant.
(End)
a(n) = Sum_{k=ceiling(n/2)..n} A003266(k) / (A003266(2*k-n) * A003266(n-k)). - Vaclav Kotesovec, Apr 30 2015

Extensions

a(14) corrected by Vaclav Kotesovec, Apr 29 2015

A238244 A recursive sequence: a(n) = Fibonacci(n)*a(n-1) + 3.

Original entry on oeis.org

1, 4, 11, 36, 183, 1467, 19074, 400557, 13618941, 749041758, 66664716465, 9599719170963, 2236734566834382, 843248931696562017, 514381848334902830373, 507694884306549093578154, 810788730237558902444311941, 2095078078933852203916102055547
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 20 2014

Keywords

Comments

Generally, sequence a(n) = Fibonacci(n)*a(n-1) + p, with a(1)=1 and fixed p, is asymptotic to c(p) * ((1+sqrt(5))/2)^(n^2/2+n/2) / 5^(n/2), where constant c(p) = A062073 * (p*A101689 - p + 1).

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[n]==Fibonacci[n]*a[n-1]+3,a[1]==1},a,{n,1,20}]
    nxt[{n_,a_}]:={n+1,a*Fibonacci[n+1]+3}; NestList[nxt,{1,1},20][[;;,2]] (* Harvey P. Dale, Sep 04 2024 *)

Formula

a(n) ~ c * ((1+sqrt(5))/2)^(n^2/2+n/2) / 5^(n/2), where c = A062073 * (3*A101689-2) = 7.4996979520811499717534... is product of Fibonacci factorial constant (see A062073) and -2+3*sum_{n>=1} 1/product(A000045(k), k=1..n).

A259314 Decimal expansion of partition factorial constant.

Original entry on oeis.org

9, 1, 1, 0, 1, 6, 7, 3, 1, 3, 3, 2, 2, 4, 9, 9, 5, 1, 8, 6, 1, 5, 4, 7, 4, 6, 9, 5, 9, 4, 6, 8, 3, 4, 5, 2, 7, 8, 0, 7, 3, 8, 6, 0, 9, 7, 8, 0, 0, 8, 0, 9, 3, 0, 2, 8, 1, 3, 2, 1, 4, 9, 0, 2, 2, 7, 5, 9, 1, 4, 9, 1, 2, 4, 0, 4, 5, 5, 5, 7, 5, 1, 1, 6, 5, 0, 2, 5, 3, 7, 0, 7, 0, 2, 7, 5, 3, 9, 2, 1, 0, 4, 4, 7, 5, 0
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 24 2015

Keywords

Examples

			0.91101673133224995186154746959468345278073860978008093028132149022759...
		

Crossrefs

Programs

  • Mathematica
    (* The iteration cycle: *) Do[Print[Product[N[PartitionsP[k]/((E^(Sqrt[2/3]*Sqrt[k-1/24]*Pi) * (1 - Sqrt[3/2]/(Sqrt[k-1/24]*Pi))) / (4*Sqrt[3]*(k-1/24))), 150], {k, 1, n}]], {n, 500, 50000, 500}]

Formula

Equals limit n->infinity Product_{k=1..n} p(k) / (exp(Pi*sqrt(2/3*(k-1/24))) / (4*sqrt(3)*(k-1/24)) * (1 - sqrt(3/(2*(k-1/24)))/Pi)), where p(k) is the partition function A000041.
Previous Showing 11-20 of 33 results. Next