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.

Previous Showing 21-26 of 26 results.

A147611 The 3rd Witt transform of A000027.

Original entry on oeis.org

0, 0, 0, 0, 2, 7, 18, 42, 84, 153, 264, 429, 666, 1001, 1456, 2061, 2856, 3876, 5166, 6783, 8778, 11214, 14168, 17710, 21924, 26910, 32760, 39582, 47502, 56637, 67122, 79112, 92752, 108207, 125664, 145299, 167310, 191919, 219336, 249795, 283556
Offset: 0

Views

Author

R. J. Mathar, Nov 08 2008

Keywords

Comments

a(n) is the number of binary Lyndon words of length n+3 having 3 blocks of 0's, see Math.SE. - Andrey Zabolotskiy, Nov 16 2021

Crossrefs

Cf. A006584 (2nd Witt transform of A000027), A049347, A099254, A147618.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50); [0,0,0,0] cat Coefficients(R!( x^4*(2-x+2*x^2)/((1-x)^6*(1+x+x^2)^2) )); // G. C. Greubel, Oct 24 2022
    
  • Mathematica
    CoefficientList[Series[x^4(2 -x+ 2*x^2)/((1-x)^6*(1 +x +x^2)^2), {x, 0, 50}], x] (* Vincenzo Librandi, Dec 13 2012 *)
  • SageMath
    def A147611_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x^4*(2-x+2*x^2)/((1-x)^6*(1+x+x^2)^2) ).list()
    A147611_list(50) # G. C. Greubel, Oct 24 2022

Formula

G.f.: x^4*(2-x+2*x^2)/((1-x)^6*(1+x+x^2)^2).
a(n) = (1/27)*((3*A049347(n) + A049347(n-1)) - 3*(-1)^n*(A099254(n) - A099254(n- 1)) + n*(3*n^4 - 15*n^2 - 28)/40). - G. C. Greubel, Oct 24 2022

A167177 Expansion of 1/((1 +x +x^2)^2 *(1 +x^2 +x^3)^3).

Original entry on oeis.org

1, -2, -2, 5, 5, -7, -13, 2, 29, 19, -47, -68, 43, 151, 31, -246, -237, 267, 611, -34, -1078, -707, 1327, 2149, -701, -4118, -1760, 5611, 6904, -4361, -14463, -3123, 21453, 20320, -20510, -47501, -426, 76389, 54711, -84119, -147200, 30748, 256922, 132152, -315913, -432648, 196632
Offset: 0

Views

Author

Roger L. Bagula, Oct 29 2009

Keywords

Crossrefs

Cf. A099254.

Programs

  • Mathematica
    a = {t^2 + t + 1, tau^2 + tau + 1, x^3 + x + 1, y^3 + y + 1, z^3 + z + 1} /. y -> x /. z -> x /. t -> x /. tau -> x
    p[x_] = Product[a[[n]], {n, 1, 5}]
    q[x_] = Expand[x^13*p[1/x]]
    Table[ SeriesCoefficient[ Series[1/q[x], {x, 0, 30}], n], {n, 0, 30}]
    CoefficientList[Series[1/((1 + x + x^2)^2*(1 + x^2 + x^3)^3), {x, 0, 100}], x] (* G. C. Greubel, Jun 04 2016 *)

Formula

a(n) = -2*a(n-1) -6*a(n-2) -11*a(n-3) -19*a(n-4) -27*a(n-5) -34*a(n-6) -38*a(n-7) -36*a(n-8) -30*a(n-9) -21*a(n-10) -12*a(n-11) -5*a(n-12) -a(n-13).

A188146 Three interleaved 1st-order polynomials: a(3*n) = 1+4*n, a(1+3*n) = 3+4*n, a(2+3*n) = 1+n.

Original entry on oeis.org

1, 3, 1, 5, 7, 2, 9, 11, 3, 13, 15, 4, 17, 19, 5, 21, 23, 6, 25, 27, 7, 29, 31, 8, 33, 35, 9, 37, 39, 10, 41, 43, 11, 45, 47, 12, 49, 51, 13, 53, 55, 14, 57, 59, 15, 61, 63, 16, 65, 67, 17, 69, 71, 18, 73, 75, 19, 77, 79, 20, 81, 83, 21, 85, 87, 22, 89, 91, 23, 93, 95, 24, 97, 99, 25, 101, 103, 26, 105, 107, 27, 109, 111
Offset: 0

Views

Author

Paul Curtz, Mar 22 2011

Keywords

Programs

  • Mathematica
    CoefficientList[Series[(1+3x+x^2+3x^3+x^4)/((x-1)^2(1+x+x^2)^2), {x,0,85}],x] (* Harvey P. Dale, Apr 09 2011 *)
  • PARI
    Vec((1+3*x+x^2+3*x^3+x^4 ) / ((x-1)^2*(1+x+x^2)^2) + O(x^100)) \\ Colin Barker, Mar 06 2017

Formula

a(n)= 2*a(n-3) - a(n-6).
a(3*n) + a(1+3*n) + a(2+3*n) = 5+9*n.
a(n) = n + 1 - (-1)^n*A099254(n-1). - R. J. Mathar, Mar 31 2011
G.f.: ( 1+3*x+x^2+3*x^3+x^4 ) / ( (x-1)^2*(1+x+x^2)^2 ). - R. J. Mathar, Mar 31 2011
a(n) = (9*(n+1) + sqrt(3)*(3*n+4)*sin((2*Pi*n)/3) + 3*n*cos((2*Pi*n)/3)) / 9. - Colin Barker, Mar 06 2017

A201947 Triangle T(n,k), read by rows, given by (1,1,-1,0,0,0,0,0,0,0,...) DELTA (1,-1,1,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 1, 1, 2, 2, 0, 3, 5, 1, -1, 5, 10, 4, -2, -1, 8, 20, 12, -4, -4, 0, 13, 38, 31, -4, -13, -2, 1, 21, 71, 73, 3, -33, -11, 3, 1, 34, 130, 162, 34, -74, -42, 6, 6, 0, 55, 235, 344, 128, -146, -130, 0, 24, 3, -1
Offset: 0

Views

Author

Philippe Deléham, Dec 06 2011

Keywords

Comments

Row-reversed variant of A123585. Row sums: 2^n.

Examples

			Triangle begins:
1
1, 1
2, 2, 0
3, 5, 1, -1
5, 10, 4, -2, -1
8, 20, 12, -4, -4, 0
13, 38, 31, -4, -13, -2, 1
21, 71, 73, 3, -33, -11, 3, 1
34, 130, 162, 34, -74, -42, 6, 6, 0
55, 235, 344, 128, -146, -130, 0, 24, 3, -1
		

Crossrefs

Cf. Columns: A000045, A001629, A129707.
Diagonals: A010892, A099254, Antidiagonal sums: A158943.

Formula

G.f.: 1/(1-(1+y)*x+(y+1)*(y-1)*x^2).
T(n,0) = A000045(n+1).
T(n,k) = T(n-1,k) + T(n-1,k-1) + T(n-2,k) - T(n-2,k-2) with T(0,0)= 1 and T(n,k)= 0 if n
Sum_{k, 0<=k<=n} T(n,k)*x^k = (-1)^n*A090591(n), (-1)^n*A106852(n), A000007(n), A000045(n+1), A000079(n), A057083(n), A190966(n+1) for n = -3, -2, -1, 0, 1, 2, 3 respectively.
Sum_{k, 0<=k<=n} T(n,k)*x^(n-k) = A010892(n), A000079(n), A030195(n+1), A180222(n+2) for x = 0, 1, 2, 3 respectively.

A238988 Triangle T(n,k), read by rows, given by (1, -1, 1, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, -1, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 1, 1, 0, 1, 1, -1, 0, 2, 1, -1, -1, 1, 2, 1, 0, -1, -2, 1, 3, 1, 1, 0, -4, -2, 3, 3, 1, 1, 1, -2, -4, -2, 3, 4, 1, 0, 1, 3, -2, -9, -2, 6, 4, 1, -1, 0, 6, 3, -9, -9, 0, 6, 5, 1, -1, -1, 3, 6, 3, -9, -15, 0, 10, 5, 1, 0, -1, -4, 3, 18, 3, -24, -15, 5, 10, 6, 1
Offset: 0

Author

Philippe Deléham, Mar 07 2014

Keywords

Comments

T(n,0) = T(n+1,1) = A010892(n), T(n+2,2) = T(n+3,3) = A099254(n), T(n+4,4) = T(n+5,5) = A128504(n).
Triangle T(n,k) = A101950(n - floor((k+1)/2),floor(k/2)).

Examples

			Triangle begins:
1;
1, 1;
0, 1, 1;
-1, 0, 2, 1;
-1, -1, 1, 2, 1;
0, -1, -2, 1, 3, 1;
1, 0, -4, -2, 3, 3, 1;
1, 1, -2, -4, -2, 3, 4, 1;
0, 1, 3, -2, -9, -2, 6, 4, 1;
-1, 0, 6, 3, -9, -9, 0, 6, 5, 1;
-1, -1, 3, 6, 3, -9, -15, 0, 10, 5, 1;
0, -1, -4, 3, 18, 3, -24, -15, 5, 10, 6, 1;
1, 0, -8, -4, 18, 18, -6, -24, -20, 5, 15, 6, 1;
		

Crossrefs

Programs

  • Mathematica
    nmax=11; Flatten[CoefficientList[Series[CoefficientList[Series[(1 + x*y)/(1 - x + x^2 - x^2*y^2), {x, 0, nmax}], x], {y, 0, nmax}], y]] (* Indranil Ghosh, Mar 14 2017 *)

Formula

G.f.: (1 + x*y)/(1 - x + x^2 - x^2*y^2).
T(n,k) = T(n-1,k) + T(n-2,k-2) - T(n-2,k), T(0,0) = T(1,0) = T(1,1) = 1, T(n,k) = 0 if k<0 or if k>n.
Sum_{k = 0..n} T(n,k)*x^k = A000007(n), A010892(n), A040000(n), A105476(n+1) for x = -1, 0, 1, 2 respectively.

A115054 G.f.: (x^3+6*x+2)^2/(x^2+x+1)^2.

Original entry on oeis.org

4, 16, -8, -36, 72, -36, -63, 126, -63, -90, 180, -90, -117, 234, -117, -144, 288, -144, -171, 342, -171, -198, 396, -198, -225, 450, -225, -252, 504, -252, -279, 558, -279, -306, 612, -306, -333, 666, -333, -360, 720, -360, -387, 774, -387, -414, 828, -414, -441, 882, -441, -468, 936, -468, -495, 990, -495
Offset: 0

Author

Roger L. Bagula, Feb 28 2006

Keywords

Comments

q=3 coefficient expansion of hierarchical lattice renormalization polynomial.
Auto-convolution of the sequence 2,4,-6,3,3,-6,3,3,.. (period length 3). [From R. J. Mathar, Mar 09 2009]

References

  • Peitgen and Richter, The Beauty of Fractals, Springer-Verlag, New York, 1986, page 146

Programs

  • Maple
    G:=(x^3+6*x+2)^2/(x^2+x+1)^2: Gser:=series(G,x=0,55): seq(coeff(Gser,x,n),n=0..50);
  • Mathematica
    q=3 b = 9*Flatten[{{4/9}, Abs[Table[Coefficient[ Series[((x^3 + 3*(q - 1)*x + (q - 1)*(q - 2))/(3*x^2 + 3*( q - 2)*x + q^2 - 3*q + 3))^2, {x, 0, 30}], x^n], {n, 1, 30}]]}]

Formula

a(n) = 18*A131713(n)-27*(-1)^n*A099254(n), n>2. [From R. J. Mathar, Mar 09 2009]

Extensions

Edited by N. J. A. Sloane, Apr 16 2006
Previous Showing 21-26 of 26 results.