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 1-8 of 8 results.

A003953 Expansion of g.f.: (1+x)/(1-10*x).

Original entry on oeis.org

1, 11, 110, 1100, 11000, 110000, 1100000, 11000000, 110000000, 1100000000, 11000000000, 110000000000, 1100000000000, 11000000000000, 110000000000000, 1100000000000000, 11000000000000000
Offset: 0

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Author

Keywords

Comments

Coordination sequence for infinite tree with valency 11.
a(n) is sequence A003945(n-1) written in base 2: a(0)=1, a(n) for n >= 1: 2 times 1, (n-1) times 0. a(n) is also A007283(n-1) and A042950(n) for n >= 1 written in base 2. a(n) is also A098011(n+3) and A101229(n+10) for n >= 1 written in base 2. a(n) is also abs(A110164(n+1)) for n >= 1 written in base 2. - Jaroslav Krizek, Aug 17 2009
a(n) equals the numbers of words of length n on alphabet {0,1,...,10} with no two adjacent letters identical. - Milan Janjic, Jan 31 2015 [Corrected by David Nacin, Jun 02 2017]

Crossrefs

Programs

Formula

a(n) = Sum_{k=0..n} A029653(n, k)*x^k for x = 9. - Philippe Deléham, Jul 10 2005
G.f.: (1+x)/(1-10*x). - Paul Barry, Mar 22 2006
a(0) = 1, a(n) = 10^n + 10^(n-1) = 11*10^(n-1) for n >= 1. - Jaroslav Krizek, Aug 17 2009
E.g.f.: (11*exp(10*x) - 1)/10. - G. C. Greubel, Sep 24 2019

Extensions

Edited by N. J. A. Sloane, Dec 04 2009

A110162 Riordan array ((1-x)/(1+x), x/(1+x)^2).

Original entry on oeis.org

1, -2, 1, 2, -4, 1, -2, 9, -6, 1, 2, -16, 20, -8, 1, -2, 25, -50, 35, -10, 1, 2, -36, 105, -112, 54, -12, 1, -2, 49, -196, 294, -210, 77, -14, 1, 2, -64, 336, -672, 660, -352, 104, -16, 1, -2, 81, -540, 1386, -1782, 1287, -546, 135, -18, 1, 2, -100, 825, -2640, 4290, -4004, 2275, -800, 170, -20, 1
Offset: 0

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Author

Paul Barry, Jul 14 2005

Keywords

Comments

Inverse of Riordan array A094527. Rows sums are A099837. Diagonal sums are A110164. Product of Riordan array A102587 and inverse binomial transform (1/(1+x), x/(1+x)).
Coefficients of polynomials related to Cartan matrices of types C_n and B_n: p(x, n) = (-2 + x)*p(x, n - 1) - p(x, n - 2), with p(x,0) = 1; p(x,1) = 2-x; p(x,2) = x^2-4*x-2. - Roger L. Bagula, Apr 12 2008
From Wolfdieter Lang, Nov 16 2012: (Start)
The alternating row sums are given in A219233.
For n >= 1 the row polynomials in the variable x^2 are R(2*n,x):=2*T(2*n,x/2) with Chebyshev's T-polynomials. See A127672 and also the triangle A127677.
(End)
From Peter Bala, Jun 29 2015: (Start)
Riordan array has the form ( x*h'(x)/h(x), h(x) ) with h(x) = x/(1 + x)^2 and so belongs to the hitting time subgroup H of the Riordan group (see Peart and Woan).
T(n,k) = [x^(n-k)] f(x)^n with f(x) = (1 - 2*x + sqrt(1 - 4*x))/2. In general the (n,k)th entry of the hitting time array ( x*h'(x)/h(x), h(x) ) has the form [x^(n-k)] f(x)^n, where f(x) = x/( series reversion of h(x) ). (End)

Examples

			Triangle T(n,k) begins:
m\k  0    1    2     3     4     5     6    7    8   9 10 ...
0:   1
1:  -2    1
2:   2   -4    1
3:  -2    9   -6     1
4:   2  -16   20    -8     1
5:  -2   25  -50    35   -10     1
6:   2  -36  105  -112    54   -12     1
7:  -2   49 -196   294  -210    77   -14    1
8:   2  -64  336  -672   660  -352   104  -16    1
9:  -2   81 -540  1386 -1782  1287  -546  135  -18   1
10:  2 -100  825 -2640  4290 -4004  2275 -800  170 -20  1
... Reformatted and extended by _Wolfdieter Lang_, Nov 16 2012
Row polynomial n=2: P(2,x) = 2 - 4*x + x^2. R(4,x):= 2*T(4,x/2) = 2 - 4*x^2 + x^4. For P and R see a comment above. - _Wolfdieter Lang_, Nov 16 2012.
		

Crossrefs

Cf. A128411. See A127677 for an almost identical triangle.

Programs

  • Magma
    /* As triangle */ [[(-1)^(n-k)*(Binomial(n+k,n-k) + Binomial(n+k-1,n-k-1)): k in [0..n]]: n in [0.. 12]]; // Vincenzo Librandi, Jun 30 2015
    
  • Mathematica
    Table[If[n==0 && k==0, 1, (-1)^(n-k)*(Binomial[n+k, n-k] + Binomial[n+k-1, n-k-1])], {n, 0, 15}, {k, 0, n}]//Flatten (* G. C. Greubel, Dec 16 2018 *)
  • PARI
    {T(n,k) = (-1)^(n-k)*(binomial(n+k,n-k) + binomial(n+k-1,n-k-1))};
    for(n=0, 12, for(k=0, n, print1(T(n,k), ", "))) \\ G. C. Greubel, Dec 16 2018
    
  • Sage
    [[(-1)^(n-k)*(binomial(n+k,n-k) + binomial(n+k-1,n-k-1)) for k in range(n+1)] for n in range(12)] # G. C. Greubel, Dec 16 2018

Formula

T(n,k) = (-1)^(n-k)*(C(n+k,n-k) + C(n+k-1,n-k-1)), with T(0,0) = 1. - Paul Barry, Mar 22 2007
From Wolfdieter Lang, Nov 16 2012: (Start)
O.g.f. row polynomials P(n,x) := Sum(T(n,k)*x^k, k=0..n): (1-z^2)/(1+(x-2)*z+z^2) (from the Riordan property).
O.g.f. column No. k: ((1-x)/(1+x))*(x/(1+x)^2)^k, k >= 0.
T(0,0) = 1, T(n,k) = (-1)^(n-k)*(2*n/(n+k))*binomial(n+k,n-k), n>=1, and T(n,k) = 0 if n < k. (From the Chebyshev T-polynomial formula due to Waring's formula.)
(End)
T(n,k) = -2*T(n-1,k) + T(n-1,k-1) - T(n-2,k), T(0,0)=1, T(n,k)=0 if k<0 or if k>n. - Philippe Deléham, Nov 29 2013

A111286 Number of permutations avoiding the patterns {1342, 1432, 2341, 2431, 3142, 3241, 3412, 3421, 4132, 4231, 4312, 4321}; number of strong sorting class based on 1342.

Original entry on oeis.org

1, 1, 2, 6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072, 6144, 12288, 24576, 49152, 98304, 196608, 393216, 786432, 1572864, 3145728, 6291456, 12582912, 25165824, 50331648, 100663296, 201326592, 402653184, 805306368, 1610612736, 3221225472
Offset: 0

Views

Author

Len Smiley, Nov 01 2005

Keywords

Crossrefs

Cf. A003945, A007283, A042950, A098011, A110164 - differs from each by one initial term.

Programs

  • Mathematica
    Table[If[n == 1, 1, If[n == 2, 2, 3*2^(n - 2)]], {n, 32}] (* Robert G. Wilson v *)
    LinearRecurrence[{2},{1,2,6},40] (* Harvey P. Dale, Jul 14 2019 *)

Formula

a(n) = 3*2^(n-2), n>=3.
a(n) = 2*a(n-1) for n=3. G.f.: (1-x+2*x^3)/(1-2*x). - Colin Barker, Nov 29 2012

Extensions

a(0)=1 prepended by Alois P. Heinz, Mar 12 2024

A010719 Period 2: repeat {5,8}.

Original entry on oeis.org

5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5, 8, 5
Offset: 0

Views

Author

N. J. A. Sloane, Dec 11 1996

Keywords

Comments

The inverse binomial transform is 5, 3, -6, 12, -24, 48, -96, 192, -384, 768, ... essentially A110164. - R. J. Mathar, Feb 25 2023

Crossrefs

Cf. A176323.

Programs

Formula

a(n) = a(n-2) for n > 1; a(0) = 5, a(1) = 8. G.f.: (5+8*x)/((1-x)*(1+x)). - Vincenzo Librandi, Aug 01 2010
a(n) = 3*(n mod 2) + 5. - Wesley Ivan Hurt, Jun 14 2014

A173457 Number of cell turned "ON" at n-th stage of cellular automaton of A173456.

Original entry on oeis.org

0, 1, 8, 12, 4, 28, 36, 4, 28, 36, 12, 84, 108, 4, 28, 36, 12, 84, 108, 12, 84, 108, 36, 252, 324, 4, 28, 36, 12, 84, 108, 12, 84, 108, 36, 252, 324, 12, 84, 108, 36, 252, 324, 36, 252, 324, 108, 756, 972, 4, 28, 36, 12, 84, 108, 12, 84, 108, 36, 252, 324
Offset: 0

Views

Author

Omar E. Pol, Feb 18 2010

Keywords

Comments

Essentially the first differences of A173456.
It appears that row lengths give A098011. After the initial zero, it appears that row lengths give the absolute values of A110164. - Omar E. Pol, Apr 22 2013

Examples

			From Omar E. Pol, Apr 22 2013 (Start):
When written as an irregular triangle begins:
0;
1;
8,12;
4,28,36;
4,28,36,12,84,108;
4,28,36,12,84,108,12,84,108,36,252,324;
4,28,36,12,84,108,12,84,108,36,252,324,12,84,108,36,252,324,36,252,324,108,756,972;
4,28,36,12,84,108,12,84,108,36,252,324,...
(End)
		

Crossrefs

Formula

a(0)=0, a(1)=1, a(2)=8, a(3)=12, for n>=4 when (n MOD 3)=0,1,2 let m=36,4,28 then a(n)=m*A147610((n + 2) / 3). (Found empirically) [Lars Blomberg, Apr 22 2013]

Extensions

a(41)-a(60) from Lars Blomberg, Apr 22 2013

A173461 Number of cells turned "ON" at n-th stage of cellular automaton of A173460.

Original entry on oeis.org

0, 1, 8, 12, 8, 52, 12, 12, 84, 36, 28, 188, 12, 12, 84, 36, 36, 252, 36, 36, 252, 108, 92, 628, 12, 12, 84, 36, 36, 252, 36, 36, 252, 108, 108, 756, 36, 36, 252, 108, 108, 756, 108, 108, 756, 324, 292, 2012, 12, 12, 84, 36, 36, 252, 36, 36, 252, 108, 108
Offset: 0

Views

Author

Omar E. Pol, Feb 18 2010

Keywords

Comments

Essentially the first differences of A173460.
It appears that row lengths give the absolute values of A110164. - Omar E. Pol, Apr 25 2013

Examples

			From _Omar E. Pol_, Apr 25 2013: (Start)
When written as an irregular triangle begins:
0;
1,8;
12,8,52;
12,12,84,36,28,188;
12,12,84,36,36,252,36,36,252,108,92,628;
12,12,84,36,36,252,36,36,252,108,108,756,36,36,252,108,108,756,108,108,756,324,292,2012;
12,12,84,36,36,252,36,36,252,108,108,...
(End)
		

Crossrefs

Formula

a(0)=0, a(1)=1, a(2)=8, for n>=3 let i=n/3+1, j=A147610(i), if 2^r==i for some r then let c1=2^(r+1), c2=2^(r+4) else let c1=c2=0, finally when (n MOD 3)=0,1,2 let a(n)=12*j, 12*j-c1, 84*j-c2. (Found empirically) [Lars Blomberg, Apr 23 2013]

Extensions

More terms a(14)-a(17) from Omar E. Pol, Sep 25 2011
a(18)-a(58) from Lars Blomberg, Apr 23 2013

A176414 Expansion of (7+8*x)/(1+2*x).

Original entry on oeis.org

7, -6, 12, -24, 48, -96, 192, -384, 768, -1536, 3072, -6144, 12288, -24576, 49152, -98304, 196608, -393216, 786432, -1572864, 3145728, -6291456, 12582912, -25165824, 50331648, -100663296, 201326592, -402653184, 805306368
Offset: 0

Views

Author

Klaus Brockhaus, Apr 17 2010

Keywords

Comments

Inverse binomial transform of A176415.

Crossrefs

Cf. A176415, A110164 (essentially the same), A122803.

Programs

  • Mathematica
    Join[{7},NestList[-2#&,-6,40]] (* Harvey P. Dale, Jun 20 2020 *)
  • PARI
    {for(n=0, 29, print1(polcoeff((7+8*x)/(1+2*x)+x*O(x^n), n), ", "))}
    
  • PARI
    A176414(n)=3*(-2)^n+!n*4 \\ M. F. Hasler, Apr 19 2015

Formula

a(n) = A110164(n+2) for n > 0.
a(n) = 3*(-2)^n = 3*A122803(n+1) for n > 0; a(0) = 7.
a(n) = -2*a(n-1) for n > 1; a(0) = 7, a(1) = -6.
a(n) = (-1)^n*A132477(n) = (-1)^n*A122391(n+3), n>1.
a(n) = (-1)^n*A111286(n+2) = (-1)^n*A098011(n+4) = (-1)^n*A091629(n) = (-1)^n*A087009(n+3) = (-1)^n*A082505(n+1) = (-1)^n*A042950(n+1) = (-1)^n*A007283(n) = (-1)^n*A003945(n+1), n>0. - R. J. Mathar, Dec 10 2010
E.g.f.: 4 + 3*exp(-2*x). - Alejandro J. Becerra Jr., Feb 15 2021

Extensions

Edited by M. F. Hasler, Apr 19 2015

A114958 a(n) = 6*2^(n+1) - 5*(n+1) - 4.

Original entry on oeis.org

3, 10, 29, 72, 163, 350, 729, 1492, 3023, 6090, 12229, 24512, 49083, 98230, 196529, 393132, 786343, 1572770, 3145629, 6291352, 12582803, 25165710, 50331529, 100663172, 201326463, 402653050, 805306229, 1610612592, 3221225323
Offset: 0

Views

Author

Creighton Dement, Feb 21 2006

Keywords

Crossrefs

Programs

  • Magma
    [6*2^(n+1) - 5*(n+1) - 4: n in [0..30] ]; // Vincenzo Librandi, May 18 2011
    
  • PARI
    Vec((3 - 2*x + 4*x^2) / ((1 - x)^2*(1 - 2*x)) + O(x^40)) \\ Colin Barker, Apr 30 2019

Formula

From Colin Barker, Apr 30 2019: (Start)
G.f.: (3 - 2*x + 4*x^2) / ((1 - x)^2*(1 - 2*x)).
a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3) for n>2.
(End)
Showing 1-8 of 8 results.