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 1-7 of 7 results.

A103333 Number of closed walks on the graph of the (7,4) Hamming code.

Original entry on oeis.org

1, 3, 24, 192, 1536, 12288, 98304, 786432, 6291456, 50331648, 402653184, 3221225472, 25769803776, 206158430208, 1649267441664, 13194139533312, 105553116266496, 844424930131968, 6755399441055744, 54043195528445952, 432345564227567616
Offset: 0

Views

Author

Paul Barry, Jan 31 2005

Keywords

Comments

Counts closed walks of length 2n at the degree 3 node of the graph of the (7,4) Hamming code. With interpolated zeros, counts paths of length n at this node.
a(n+1) = A157176(A016945(n)). - Reinhard Zumkeller, Feb 24 2009
For n>0: a(n) = A083713(n) - A083713(n-1). - Reinhard Zumkeller, Feb 22 2010

References

  • David J.C. Mackay, Information Theory, Inference and Learning Algorithms, CUP, 2003, p. 19

Crossrefs

Cf. A000302, A004171. - Vincenzo Librandi, Jan 22 2009

Programs

Formula

G.f.: (1-5*x)/(1-8*x);
a(n) = (3*8^n + 5*0^n)/8.
a(n) = 8*a(n-1) for n > 0. - Harvey P. Dale, Mar 02 2012

A083076 Third row of number array A083075.

Original entry on oeis.org

1, 5, 33, 229, 1601, 11205, 78433, 549029, 3843201, 26902405, 188316833, 1318217829, 9227524801, 64592673605, 452148715233, 3165041006629, 22155287046401, 155087009324805, 1085609065273633, 7599263456915429, 53194844198408001
Offset: 0

Views

Author

Paul Barry, Apr 23 2003

Keywords

Comments

Binomial transform of A067411. Inverse binomial transform of A082412.
Trinomial transform of Jacobsthal numbers A001045. - Paul Barry, Sep 10 2007

Crossrefs

Programs

Formula

a(n) = (2*7^n + 1)/3.
G.f.: (1-3*x)/((1-x)*(1-7*x)).
E.g.f.: (2*exp(7*x) + exp(x))/3.
a(n) = Sum_{k=0..2*n} trinomial(n,k)*Fibonacci(k+1), where trinomial(n,k) are the trinomial coefficients (A027907). - Paul Barry, Sep 10 2007
a(n) = 7*a(n-1) - 2, a(n) = 8*a(n-1) - 7*a(n-2). - Vincenzo Librandi, Nov 06 2011

A082413 a(n) = (2*9^n + 3^n)/3.

Original entry on oeis.org

1, 7, 57, 495, 4401, 39447, 354537, 3189375, 28700001, 258286887, 2324542617, 20920765455, 188286534801, 1694577750327, 15251196564297, 137260759512735, 1235346806916801, 11118121176157767, 100063090327139577, 900567812169415215
Offset: 0

Views

Author

Paul Barry, Apr 23 2003

Keywords

Comments

Binomial transform of A082412.

Crossrefs

Programs

Formula

G.f.: (1-5*x)/((1-3*x)*(1-9*x));
E.g.f.: (2*exp(9*x) + exp(3*x))/3.
a(n) = (2*9^n + 3^n)/3.

A103334 Number of closed walks of length 2n at any of the nodes of degree 1 on the graph of the (7,4) Hamming code.

Original entry on oeis.org

1, 1, 4, 24, 176, 1376, 10944, 87424, 699136, 5592576, 44739584, 357914624, 2863312896, 22906494976, 183251943424, 1466015514624, 11728124051456, 93824992280576, 750599937982464, 6004799503335424, 48038396025634816
Offset: 0

Views

Author

Paul Barry, Jan 31 2005

Keywords

Comments

a(n+1)=8^n/3+2^(n+1)/3 with g.f. (1-6x)/(1-10x+16x^2) counts walks of length 2n+1 between adjacent nodes of degrees 1 and 4 on the graph of the (7,4) Hamming code.

References

  • David J.C. Mackay, Information Theory, Inference and Learning Algorithms, CUP, 2003, p. 19.

Crossrefs

Formula

G.f.: (1-9x+10x^2)/(1-10x+16x^2); a(n)=8^(n-1)/3+2^(n)/3+5*0^n/8.

A082414 a(n) = (2*10^n + 4^n)/3.

Original entry on oeis.org

1, 8, 72, 688, 6752, 67008, 668032, 6672128, 66688512, 666754048, 6667016192, 66668064768, 666672259072, 6666689036288, 66666756145152, 666667024580608, 6666668098322432, 66666672393289728, 666666689573158912, 6666666758292635648
Offset: 0

Views

Author

Paul Barry, Apr 23 2003

Keywords

Comments

Binomial transform of A082413.

Crossrefs

Programs

Formula

G.f.: (1-6*x)/((1-4*x)*(1-10*x)).
E.g.f.: (2*exp(10*x) + exp(4*x))/3.
a(n) = (2*10^n + 4^n)/3.

A083217 a(n) = (2*5^n + (-1)^n)/3.

Original entry on oeis.org

1, 3, 17, 83, 417, 2083, 10417, 52083, 260417, 1302083, 6510417, 32552083, 162760417, 813802083, 4069010417, 20345052083, 101725260417, 508626302083, 2543131510417, 12715657552083, 63578287760417, 317891438802083
Offset: 0

Views

Author

Paul Barry, Apr 23 2003

Keywords

Comments

Binomial transform of A003683 (without leading zero). Inverse binomial transform of A067411.
a(n) is the number of compositions of n when there are 3 types of 1 and 8 types of other natural numbers. - Milan Janjic, Aug 13 2010

Crossrefs

Programs

  • Magma
    [(2*5^n +(-1)^n)/3: n in [0..40]]; // G. C. Greubel, Feb 17 2023
  • Mathematica
    LinearRecurrence[{4,5},{1,3},30] (* Harvey P. Dale, Sep 18 2018 *)
  • Sage
    from sage.combinat.sloane_functions import recur_gen2b
    it = recur_gen2b(1,3,4,5, lambda n: 0)
    [next(it) for i in range(1,24)] # Zerinvary Lajos, Jul 03 2008
    

Formula

a(n) = (2*5^n + (-1)^n)/3.
G.f.: (1-x)/((1-5*x)*(1+x)).
E.g.f.: (2*exp(5*x) + exp(-x))/3
a(n) = Sum_{k=0..n} Sum_{j=0..n-k} C(n,j)*C(n-j,k)*J(n-j+1) where J(n) = A001045(n). - Paul Barry, May 19 2006
a(0)=1, a(n) = 5*a(n-1) - 2 if n is odd, and a(n) = 5*a(n) + 2 if n is even. - Vincenzo Librandi, Nov 18 2010

A083333 a(n) = 10*a(n-2) - 16*a(n-4) for n>=4, with a(0)=a(1)=1, a(2)=6, a(3)=10.

Original entry on oeis.org

1, 1, 6, 10, 44, 84, 344, 680, 2736, 5456, 21856, 43680, 174784, 349504, 1398144, 2796160, 11184896, 22369536, 89478656, 178956800, 715828224, 1431655424, 5726623744, 11453245440, 45812985856, 91625967616, 366503878656
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Apr 24 2003

Keywords

Crossrefs

Cf. A016131, A082412 (bisections).

Programs

  • Magma
    I:=[1,1,6,10]; [n le 4 select I[n] else 10*Self(n-2) -16*Self(n-4): n in [1..41]]; // G. C. Greubel, Dec 27 2024
    
  • Mathematica
    CoefficientList[Series[(1+x-4x^2)/(1-10x^2+16x^4), {x, 0, 30}], x]
    LinearRecurrence[{0,10,0,-16},{1,1,6,10},30] (* Harvey P. Dale, Aug 04 2024 *)
  • SageMath
    def A083333(n): return 2^((n-1)/2)*( (n%2)*(2^(n+1) -1) + ((n+1)%2)*sqrt(2)*(2^(n+1) +1))/3
    print([A083333(n) for n in range(41)]) # G. C. Greubel, Dec 27 2024

Formula

G.f.: (1+x-4*x^2)/(1-10*x^2+16*x^4).
Limit_{n -> oo} A083332(n)/a(n) = 3.
a(n) = A001045(n+1)*A016116(n). - R. J. Mathar, Jul 08 2009
From G. C. Greubel, Dec 27 2024: (Start)
a(n) = (1/3)*2^((n-3)/2)*( (1-(-1)^n)*(2^(n+1) - 1) + (1+(-1)^n)*sqrt(2)*(2^(n+1) + 1) ).
E.g.f.: (1/3)*(2*cosh(2*sqrt(2)*x) + cosh(sqrt(2)*x)) + (1/(3*sqrt(2)))*(2*sinh(2*sqrt(2)*x) - sinh(sqrt(2)*x)). (End)
Showing 1-7 of 7 results.