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.

A164265 Partial sums of A162766.

Original entry on oeis.org

4, 7, 19, 28, 64, 91, 199, 280, 604, 847, 1819, 2548, 5464, 7651, 16399, 22960, 49204, 68887, 147619, 206668, 442864, 620011, 1328599, 1860040, 3985804, 5580127, 11957419, 16740388, 35872264, 50221171, 107616799, 150663520, 322850404
Offset: 1

Views

Author

Klaus Brockhaus, Aug 11 2009

Keywords

Crossrefs

Cf. A162766, A164123 (partial sums of A162436).

Programs

  • Magma
    T:=[ n le 2 select 5-n else 3*Self(n-2): n in [1..33] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];
    
  • Mathematica
    LinearRecurrence[{1,3,-3},{4,7,19},40] (* Harvey P. Dale, Aug 28 2016 *)
  • PARI
    a(n)=if(n%2,15,7)*3^(n\2)\2-3 \\ Charles R Greathouse IV, Jul 15 2011

Formula

a(n) = 3*a(n-2)+7 for n > 2; a(1) = 4, a(2) = 7.
a(n) = (11-4*(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2-7/2.
G.f.: x*(4+3*x)/((1-x)*(1-3*x^2)).

A153594 a(n) = ((4 + sqrt(3))^n - (4 - sqrt(3))^n)/(2*sqrt(3)).

Original entry on oeis.org

1, 8, 51, 304, 1769, 10200, 58603, 336224, 1927953, 11052712, 63358307, 363181200, 2081791609, 11932977272, 68400527259, 392075513536, 2247397253921, 12882196355400, 73841406542227, 423262699717616, 2426163312691977, 13906891405206808
Offset: 1

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Dec 29 2008

Keywords

Comments

Second binomial transform of A054491. Fourth binomial transform of 1 followed by A162766 and of A074324 without initial term 1.
First differences are in A161728.
Lim_{n -> infinity} a(n)/a(n-1) = 4 + sqrt(3) = 5.73205080756887729....

Crossrefs

Cf. A002194 (decimal expansion of sqrt(3)), A054491, A074324, A161728, A162766.

Programs

  • Magma
    Z:= PolynomialRing(Integers()); N:=NumberField(x^2-3); S:=[ ((4+r)^n-(4-r)^n)/(2*r): n in [1..21] ]; [ Integers()!S[j]: j in [1..#S] ];  // Klaus Brockhaus, Dec 31 2008
    
  • Magma
    I:=[1,8]; [n le 2 select I[n] else 8*Self(n-1)-13*Self(n-2): n in [1..25]]; // Vincenzo Librandi, Aug 23 2016
    
  • Mathematica
    Join[{a=1,b=8},Table[c=8*b-13*a;a=b;b=c,{n,60}]] (* Vladimir Joseph Stephan Orlovsky, Jan 19 2011 *)
    LinearRecurrence[{8,-13},{1,8},40] (* Harvey P. Dale, Aug 16 2012 *)
  • PARI
    a(n)=([0,1; -13,8]^(n-1)*[1;8])[1,1] \\ Charles R Greathouse IV, Sep 04 2016
  • Sage
    [lucas_number1(n,8,13) for n in range(1, 22)] # Zerinvary Lajos, Apr 23 2009
    

Formula

G.f.: x/(1 - 8*x + 13*x^2). - Klaus Brockhaus, Dec 31 2008, corrected Oct 11 2009
a(n) = 8*a(n-1) - 13*a(n-2) for n > 1; a(0)=0, a(1)=1. - Philippe Deléham, Jan 01 2009
E.g.f.: sinh(sqrt(3)*x)*exp(4*x)/sqrt(3). - Ilya Gutkovskiy, Aug 23 2016
a(n) = Sum_{k=0..n-1} A027907(n,2k+1)*3^k. - J. Conrad, Aug 30 2016
a(n) = Sum_{k=0..n-1} A083882(n-1-k)*4^k. - J. Conrad, Sep 03 2016

Extensions

Extended beyond a(7) by Klaus Brockhaus, Dec 31 2008
Edited by Klaus Brockhaus, Oct 11 2009

A074324 a(2n+1) = 3^n, a(2n) = 4*3^(n-1) except for a(0) = 1.

Original entry on oeis.org

1, 1, 4, 3, 12, 9, 36, 27, 108, 81, 324, 243, 972, 729, 2916, 2187, 8748, 6561, 26244, 19683, 78732, 59049, 236196, 177147, 708588, 531441, 2125764, 1594323, 6377292, 4782969, 19131876, 14348907, 57395628, 43046721, 172186884, 129140163
Offset: 0

Views

Author

Y. Kelly Itakura (yitkr(AT)mta.ca), Aug 21 2002

Keywords

Comments

Also: Coefficient of the highest power of q in the expansion of nu(0)=1, nu(1)=b and for n>=2, nu(n)=b*nu(n-1)+lambda*(n-1)_q*nu(n-2) with (b,lambda)=(1,3), where (n)_q=(1+q+...+q^(n-1)) and q is a root of unity.
Instead of listing the coefficients of the highest power of q in each nu(n), if we list the coefficients of the smallest power of q (i.e., constant terms), we get a weighted Fibonacci numbers described by f(0)=1, f(1)=1, for n>=2, f(n)=f(n-1)+3f(n-2).
Sequences A162766, A166552 are essentially the same. - M. F. Hasler, Dec 03 2014

Examples

			nu(0)=1;
nu(1)=1;
nu(2)=4;
nu(3)=7+3q;
nu(4)=19+15q+12q^2;
nu(5)=40+45q+42q^2+30q^3+9q^4;
nu(6)=97+147q+180q^2+168q^3+147q^4+81q^5+36q^6;
by listing the coefficients of the highest power in each nu(n), we get, 1,1,4,3,12,9,36,....
		

Crossrefs

Cf. A006130.

Programs

  • Magma
    [1] cat [(1/6)*(7+(-1)^n)*3^Floor(n/2):n in [1..40]]; // Vincenzo Librandi, Jul 20 2013
    
  • Mathematica
    CoefficientList[Series[-(1 + x + x^2) / (-1 + 3 x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 20 2013 *)
    LinearRecurrence[{0,3},{1,1,4},40] (* Harvey P. Dale, Mar 13 2016 *)
  • PARI
    a(n)=3^(n\2)\(3/4)^!bittest(n,0) \\ M. F. Hasler, Dec 03 2014

Formula

For given b and lambda, the recurrence relation is given by; t(0)=1, t(1)=b, t(2)=b^2+lambda and for n>=3, t(n) = lambda*t(n-2).
G.f.: -(1+x+x^2)/(-1+3*x^2). - R. J. Mathar, Dec 05 2007
a(n) = 3*a(n-2) for n>2. - Ralf Stephan, Jul 19 2013
a(n) = (1/6)*(7+(-1)^n)*3^floor(n/2) for n>0. - Ralf Stephan, Jul 19 2013

Extensions

More terms from R. J. Mathar, Dec 05 2007
Simpler definition from M. F. Hasler, Dec 03 2014

A162813 a(n) = 3*a(n-2) for n > 2; a(1) = 5, a(2) = 3.

Original entry on oeis.org

5, 3, 15, 9, 45, 27, 135, 81, 405, 243, 1215, 729, 3645, 2187, 10935, 6561, 32805, 19683, 98415, 59049, 295245, 177147, 885735, 531441, 2657205, 1594323, 7971615, 4782969, 23914845, 14348907, 71744535, 43046721, 215233605, 129140163, 645700815, 387420489
Offset: 1

Views

Author

Klaus Brockhaus, Jul 20 2009

Keywords

Comments

Binomial transform is A162562.

Crossrefs

Programs

  • Magma
    [ n le 2 select 7-2*n else 3*Self(n-2): n in [1..34] ];
  • Mathematica
    nxt[{a_,b_}]:={b,3a}; NestList[nxt,{5,3},40][[All,1]] (* or *) LinearRecurrence[ {0,3},{5,3},40] (* Harvey P. Dale, May 29 2021 *)

Formula

a(n) = (3-2*(-1)^n)*3^(1/4*(2*n-1+(-1)^n)).
G.f.: x*(5+3*x)/(1-3*x^2)

Extensions

a(35)-a(36) from Yifan Xie, Jul 20 2022

A162852 a(n) = 3*a(n-2) for n > 2; a(1) = 3, a(2) = -1.

Original entry on oeis.org

3, -1, 9, -3, 27, -9, 81, -27, 243, -81, 729, -243, 2187, -729, 6561, -2187, 19683, -6561, 59049, -19683, 177147, -59049, 531441, -177147, 1594323, -531441, 4782969, -1594323, 14348907, -4782969, 43046721, -14348907, 129140163
Offset: 1

Views

Author

Klaus Brockhaus, Jul 14 2009

Keywords

Comments

Third binomial transform is A162560.
Equivalently, 3^n followed by -3^(n-1), n > 0. - Muniru A Asiru, Oct 25 2018

Crossrefs

Programs

  • GAP
    a:=[3,-1];; for n in [3..25] do a[n]:=3*a[n-2]; od; a; # Muniru A Asiru, Oct 25 2018
  • Magma
    [ n le 2 select 7-4*n else 3*Self(n-2): n in [1..34] ];
    
  • Maple
    seq(op([3^n,-3^(n-1)]),n=1..18); # Muniru A Asiru, Oct 25 2018
  • Mathematica
    Rest[CoefficientList[Series[x*(3-x)/(1-3*x^2), {x, 0, 40}], x]] (* or *) LinearRecurrence[{0,3}, {3,-1}, 40] (* G. C. Greubel, Oct 24 2018 *)
  • PARI
    x='x+O('x^40); Vec(x*(3-x)/(1-3*x^2)) \\ G. C. Greubel, Oct 24 2018
    

Formula

a(n) = ((4-5*(-1)^n)*3^(1/4*(2*n-1+(-1)^n)))/3.
G.f.: x*(3-x)/(1-3*x^2). [corrected by Klaus Brockhaus, Sep 18 2009]
E.g.f.: (1 - cosh(sqrt(3)*x) + 3*sqrt(3)*sinh(sqrt(3)*x))/3. - G. C. Greubel, Oct 24 2018

A166552 a(n) = 3*a(n-2) for n > 2; a(1) = 1; a(2) = 4.

Original entry on oeis.org

1, 4, 3, 12, 9, 36, 27, 108, 81, 324, 243, 972, 729, 2916, 2187, 8748, 6561, 26244, 19683, 78732, 59049, 236196, 177147, 708588, 531441, 2125764, 1594323, 6377292, 4782969, 19131876, 14348907, 57395628, 43046721, 172186884, 129140163
Offset: 1

Views

Author

Klaus Brockhaus, Oct 16 2009

Keywords

Comments

Interleaving of A000244 (powers of 3) and 4*A000244.
a(n) = A074324(n); A074324 has the additional term a(0)=1.
First differences are in A162852.
Second binomial transform is A054491. Fourth binomial transform is A153594.

Crossrefs

Equals A162766 preceded by 1.
Cf. A000244 (powers of 3), A074324, A162852, A054491, A153594.

Programs

  • Magma
    [ n le 2 select 3*n-2 else 3*Self(n-2): n in [1..35] ];
    
  • Mathematica
    LinearRecurrence[{0, 3}, {1, 4}, 50] (* G. C. Greubel, May 17 2016 *)
  • PARI
    a(n)=3^(n\2)*(4/3)^!bittest(n,0) \\ M. F. Hasler, Dec 03 2014

Formula

a(n) = (7+(-1)^n)*3^(1/4*(2*n-5+(-1)^n))/2.
G.f.: x*(1+4*x)/(1-3*x^2).
a(n+3) = a(n+2)*a(n+1)/a(n). - Reinhard Zumkeller, Mar 04 2011
a(n) = 3^floor((n-1)/2)*4^(1-n%2). - M. F. Hasler, Dec 03 2014
E.g.f.: (sqrt(3)*sinh(sqrt(3)*x) + 4*cosh(sqrt(3)*x) - 4)/3. - Ilya Gutkovskiy, May 17 2016

A162559 a(n) = ((4+sqrt(3))*(1+sqrt(3))^n + (4-sqrt(3))*(1-sqrt(3))^n)/2.

Original entry on oeis.org

4, 7, 22, 58, 160, 436, 1192, 3256, 8896, 24304, 66400, 181408, 495616, 1354048, 3699328, 10106752, 27612160, 75437824, 206099968, 563075584, 1538351104, 4202853376, 11482408960, 31370524672, 85705867264, 234152783872, 639717302272, 1747740172288, 4774914949120
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Jul 06 2009

Keywords

Comments

Binomial transform of A162766. Inverse binomial transform of A077236.

Crossrefs

Programs

  • Magma
    Z:=PolynomialRing(Integers()); N:=NumberField(x^2-3); S:=[ ((4+r)*(1+r)^n+(4-r)*(1-r)^n)/2: n in [0..25] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 13 2009
  • Maple
    seq((1/2)*simplify((4+sqrt(3))*(1+sqrt(3))^n+(4-sqrt(3))*(1-sqrt(3))^n), n = 0 .. 27); # Emeric Deutsch, Jul 16 2009
  • Mathematica
    LinearRecurrence[{2,2},{4,7},30] (* Harvey P. Dale, Sep 21 2018 *)

Formula

a(n) = 2*a(n-1) + 2*a(n-2) for n > 1; a(0) = 4, a(1) = 7.
G.f.: (4-x)/(1-2*x-2*x^2).

Extensions

Edited by Klaus Brockhaus, Paolo P. Lava and Emeric Deutsch, Jul 13 2009
Two different extensions were received. This version was rechecked by N. J. A. Sloane, Jul 19 2009

A162561 a(n) = ((4+sqrt(3))*(5+sqrt(3))^nv+v(4-sqrt(3))*(5-sqrt(3))^n)/2.

Original entry on oeis.org

4, 23, 142, 914, 6016, 40052, 268168, 1800536, 12105664, 81444848, 548123872, 3689452064, 24835795456, 167190009152, 1125512591488, 7576945713536, 51008180122624, 343388995528448, 2311709992586752, 15562542024241664
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Jul 06 2009

Keywords

Comments

Third binomial transform of A077236. Fourth binomial transform of A162559. Fifth binomial transform of A162766.

Crossrefs

Programs

  • Magma
    Z:=PolynomialRing(Integers()); N:=NumberField(x^2-3); S:=[ ((4+r)*(5+r)^n+(4-r)*(5-r)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 14 2009
  • Mathematica
    LinearRecurrence[{10,-22},{4,23},30] (* Harvey P. Dale, Mar 27 2013 *)

Formula

a(n) = 10*a(n-1) - 22*a(n-2) for n > 2; a(0) = 4, a(1) = 23.
G.f.: (4-17*x)/(1-10*x+22*x^2).

Extensions

Edited and extended beyond a(5) by Klaus Brockhaus, Jul 14 2009

A164311 a(n) = 12*a(n-1) - 33*a(n-2) for n > 1; a(0) = 4, a(1) = 27.

Original entry on oeis.org

4, 27, 192, 1413, 10620, 80811, 619272, 4764501, 36738036, 283627899, 2191179600, 16934434533, 130904287596, 1012015111563, 7824339848088, 60495579495477, 467743738958820, 3616570744155099, 27963305544220128, 216212831973523269
Offset: 0

Views

Author

Klaus Brockhaus, Aug 12 2009

Keywords

Comments

Binomial transform of A162561. Sixth binomial transform of A162766.

Crossrefs

Programs

  • Magma
    [ n le 2 select 23*n-19 else 12*Self(n-1)-33*Self(n-2): n in [1..20] ];
    
  • Mathematica
    LinearRecurrence[{12,-33}, {4,27}, 50] (* or *) CoefficientList[Series[(4 - 21*x)/(1 - 12*x + 33*x^2), {x,0,50}], x] (* G. C. Greubel, Sep 13 2017 *)
  • PARI
    x='x+O('x^50); Vec((4-21*x)/(1-12*x+33*x^2)) \\ G. C. Greubel, Sep 13 2017

Formula

a(n) = ((4+sqrt(3))*(6+sqrt(3))^n + (4-sqrt(3))*(6-sqrt(3))^n)/2.
G.f.: (4-21*x)/(1-12*x+33*x^2).
E.g.f.: (4*cosh(sqrt(3)*x) + sqrt(3)*sinh(sqrt(3)*x))*exp(6*x). - G. C. Greubel, Sep 13 2017
Showing 1-9 of 9 results.