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 1-3 of 3 results.

A163888 a(n) = 2*a(n-2) for n > 2; a(1) = 5, a(2) = 4.

Original entry on oeis.org

5, 4, 10, 8, 20, 16, 40, 32, 80, 64, 160, 128, 320, 256, 640, 512, 1280, 1024, 2560, 2048, 5120, 4096, 10240, 8192, 20480, 16384, 40960, 32768, 81920, 65536, 163840, 131072, 327680, 262144, 655360, 524288, 1310720, 1048576, 2621440, 2097152, 5242880
Offset: 1

Views

Author

Klaus Brockhaus, Aug 06 2009

Keywords

Comments

Interleaving of A020714 and A000079 without initial terms 1 and 2.
Binomial transform is A163607, second binomial transform is A163608, third binomial transform is A163609, fourth binomial transform is A163610, fifth binomial transform is A163611.

Crossrefs

Cf. A020714 (5*2^n), A000079 (powers of 2), A163607, A163608, A163609, A163610, A163611.

Programs

  • Magma
    [ n le 2 select 6-n else 2*Self(n-2): n in [1..41] ];
    
  • Mathematica
    Transpose[NestList[{Last[#],2First[#]}&,{5,4},40]] [[1]]  (* Harvey P. Dale, Mar 14 2011 *)
    LinearRecurrence[{0, 2},{5, 4},41] (* Ray Chandler, Aug 14 2015 *)
  • PARI
    x='x+O('x^50); vec(x*(5+4*x)/(1-2*x^2)) \\ G. C. Greubel, Aug 07 2017

Formula

a(n) = (7 - 3*(-1)^n)*2^((2*n-5+(-1)^n)/4).
G.f.: x*(5+4*x)/(1-2*x^2).

A163608 a(n) = ((5 + 2*sqrt(2))*(2 + sqrt(2))^n + (5 - 2*sqrt(2))*(2 - sqrt(2))^n)/2.

Original entry on oeis.org

5, 14, 46, 156, 532, 1816, 6200, 21168, 72272, 246752, 842464, 2876352, 9820480, 33529216, 114475904, 390845184, 1334428928, 4556025344, 15555243520, 53108923392, 181325206528, 619082979328, 2113681504256, 7216560058368
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Aug 01 2009

Keywords

Comments

Binomial transform of A163607. Inverse binomial transform of A163609.

Crossrefs

Programs

  • Magma
    Z:= PolynomialRing(Integers()); N:=NumberField(x^2-2); S:=[ ((5+2*r)*(2+r)^n+(5-2*r)*(2-r)^n)/2: n in [0..23] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 06 2009
    
  • Mathematica
    LinearRecurrence[{4,-2},{5,14},30] (* Harvey P. Dale, Jan 31 2017 *)
  • PARI
    x='x+O('x^50); Vec((5-6*x)/(1-4*x+2*x^2)) \\ G. C. Greubel, Jul 29 2017

Formula

a(n) = 4*a(n-1) - 2*a(n-2) for n > 1; a(0) = 5, a(1) = 14.
G.f.: (5-6*x)/(1-4*x+2*x^2).
a(n) = 5*A007070(n) - 6*A007070(n-1). - R. J. Mathar, Nov 08 2013
E.g.f.: exp(2*x)*( 5*cosh(sqrt(2)*x) + 2*sqrt(2)*sinh(sqrt(2)*x) ). - G. C. Greubel, Jul 29 2017

Extensions

Edited and extended beyond a(5) by Klaus Brockhaus, Aug 06 2009

A163610 a(n) = ((5 + 2*sqrt(2))*(4 + sqrt(2))^n + (5 - 2*sqrt(2))*(4 - sqrt(2))^n)/2.

Original entry on oeis.org

5, 24, 122, 640, 3412, 18336, 98920, 534656, 2892368, 15653760, 84736928, 458742784, 2483625280, 13446603264, 72802072192, 394164131840, 2134084044032, 11554374506496, 62557819435520, 338701312393216, 1833801027048448
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Aug 01 2009

Keywords

Comments

Binomial transform of A163609. Fourth binomial transform of A163888. Inverse binomial transform of A163611.

Crossrefs

Programs

  • Magma
    Z:= PolynomialRing(Integers()); N:=NumberField(x^2-2); S:=[ ((5+2*r)*(4+r)^n+(5-2*r)*(4-r)^n)/2: n in [0..20] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 06 2009
    
  • Mathematica
    LinearRecurrence[{8,-14},{5,24},30] (* Harvey P. Dale, May 29 2016 *)
  • PARI
    x='x+O('x^50); Vec((5-16*x)/(1-8*x+14*x^2)) \\ G. C. Greubel, Jul 29 2017

Formula

a(n) = 8*a(n-1) - 14*a(n-2) for n > 1; a(0) = 5, a(1) = 24.
G.f.: (5-16*x)/(1-8*x+14*x^2).
E.g.f.: exp(4*x)*( 5*cosh(sqrt(2)*x) + 2*sqrt(2)*sinh(sqrt(2)*x) ). - G. C. Greubel, Jul 29 2017

Extensions

Edited and extended beyond a(5) by Klaus Brockhaus, Aug 06 2009
Showing 1-3 of 3 results.