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 1-2 of 2 results.

A092896 Related to random walks on the 4-cube.

Original entry on oeis.org

1, 1, 5, 17, 65, 257, 1025, 4097, 16385, 65537, 262145, 1048577, 4194305, 16777217, 67108865, 268435457, 1073741825, 4294967297, 17179869185, 68719476737, 274877906945, 1099511627777, 4398046511105, 17592186044417, 70368744177665, 281474976710657
Offset: 0

Views

Author

Paul Barry, Mar 12 2004

Keywords

Comments

Gives the denominators in the probability that a random walk on the 4-cube returns to its starting corner on the 2n-th step. Partial sums of A092898. Binomial transform of A092897.
Palindromic numbers in base 2 with an odd number of bits that can be written as 2^(2n) + 1, n >= 1. Palindromic numbers in base 2 with an even number of bits that can be written as 2^(2n+1) + 1 are A087289. - Brad Clardy, Feb 18 2014

Crossrefs

Programs

  • Magma
    [n lt 2 select 1 else 4^(n-1) +1: n in [0..30]]; // G. C. Greubel, Feb 21 2021
  • Maple
    A092896:= n -> `if`(n<2, 1, 4^(n-1) +1); seq(A092896(n), n = 0..30); # G. C. Greubel, Feb 21 2021
  • Mathematica
    CoefficientList[Series[(1 -4x +4x^2 -4x^3)/((1-x)(1-4x)), {x, 0, 40}], x] (* Vincenzo Librandi, Feb 20 2014 *)
    LinearRecurrence[{5,-4}, {1,1,5,17}, 30] (* Harvey P. Dale, Mar 19 2016 *)
  • PARI
    Vec((1-4*x+4*x^2-4*x^3)/((1-x)*(1-4*x)) + O(x^30)) \\ Colin Barker, Nov 25 2016
    
  • Sage
    [1 if n<2 else 4^(n-1) +1 for n in [0..30]]; # G. C. Greubel, Feb 21 2021
    

Formula

G.f.: (1 - 4*x + 4*x^2 - 4*x^3)/((1-x)*(1-4*x)).
a(n) = 1 + 4^n/4 - 0^n/4 + Sum_{k=0..n} binomial(n, k)*k*(-1)^k.
a(n+1) = 4^n + 1 - 0^n = A002450(n+1) - 4*A002450(n-1). - Paul Barry, Mar 13 2008
a(n) = A052539(n-1), n > 1. - R. J. Mathar, Sep 08 2008
Dropping a(0) and interleaving the terms with zeros gives a sequence with e.g.f. (sin(5ix/2)/sin(ix/2) - 3)/2 = cos(2ix) + cos(ix) - 1. Similar expressions apply to A091775 and A074515, which are also power sums representable by the Bernoulli polynomials. - Tom Copeland, Oct 22 2008
a(n) = 4^(n-1) + 1 for n > 1. - Colin Barker, Nov 25 2016
E.g.f.: (exp(4*x) + 4*exp(x) - 1 - 4*x)/4. - G. C. Greubel, Feb 21 2021

A091775 1 + 4^n + 9^n + 16^n.

Original entry on oeis.org

30, 354, 4890, 72354, 1108650, 17312754, 273234810, 4338079554, 69107159370, 1102999460754, 17623571298330, 281757423024354, 4506141560307690, 72080471098818354, 1153127396812683450, 18448597098193370754, 295164582378232361610, 4722516577573661689554
Offset: 1

Views

Author

Benoit Cloitre, Mar 06 2004

Keywords

Crossrefs

Programs

  • Magma
    [1+4^n+9^n+16^n : n in [1..20]]; // Wesley Ivan Hurt, Nov 26 2014
  • Maple
    A091775:=n->1+4^n+9^n+16^n: seq(A091775(n), n=1..20); # Wesley Ivan Hurt, Nov 26 2014
  • Mathematica
    Table[1 + 4^n + 9^n + 16^n, {n, 20}] (* or *) LinearRecurrence[ {30, -273, 820, -576}, {30, 354, 4890, 72354}, 20] (* Harvey P. Dale, May 04 2011 *)

Formula

For n > 0, a(n) = 5^(2*n+1)/(2*n+1)*sum(k = 0, 2*n + 1, (1/5)^k*C(2*n + 1, k)*B(k)) where B(k) is the k-th Bernoulli number.
G.f.: x*(16/(1 - 16*x) + 9/(1 - 9*x) + 4/(1 - 4*x) + 1/(1 - x)). - Harvey P. Dale, May 04 2011
a(1) = 30, a(2) = 354, a(3) = 4890, a(4) = 72354, a(n) = 30*a(n-1) - 273*a(n-2) + 820*a(n-3) - 576*a(n-4). - Harvey P. Dale, May 04 2011

Extensions

Corrected and extended by Harvey P. Dale, May 04 2011
Showing 1-2 of 2 results.