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.

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A120463 Expansion of x*(1+x+2*x^3) / ((x-1)*(1+x)*(3*x^2-1)).

Original entry on oeis.org

0, 1, 1, 4, 6, 13, 21, 40, 66, 121, 201, 364, 606, 1093, 1821, 3280, 5466, 9841, 16401, 29524, 49206, 88573, 147621, 265720, 442866, 797161, 1328601, 2391484, 3985806, 7174453, 11957421, 21523360, 35872266, 64570081, 107616801, 193710244
Offset: 0

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Author

Roger L. Bagula and Gary W. Adamson, Jun 30 2006

Keywords

Comments

Top element of the vector obtained by multiplying the n-th power of the 5 X 5 matrix [[0, 1, 0, 0, 0], [1, 0, 1, 0, 0], [0, 1, 0, 1, 0], [0, 0, 1, 0, 1], [0, 0, 0, 1, 0]] by the column vector [0, 1, 1, 2, 3].

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0,4,0,-3},{0,1,1,4,6},40] (* Harvey P. Dale, Dec 15 2018 *)

Formula

G.f.: x*(1+x+2*x^3) / ((x-1)*(1+x)*(3*x^2-1)).
a(2n+2) = A134931(n). a(2n+1) = A003462(n+1). - R. J. Mathar, Nov 07 2011

A166124 Triangle, read by rows, given by [0,1/2,1/2,0,0,0,0,0,0,0,...] DELTA [2,-1,0,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 2, 0, 1, 2, 0, 1, 1, 2, 0, 1, 1, 1, 2, 0, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2
Offset: 0

Views

Author

Philippe Deléham, Oct 07 2009

Keywords

Examples

			Triangle begins :
1 ;
0,2 ;
0,1,2 ;
0,1,1,2 ;
0,1,1,1,2 ;
0,1,1,1,1,2 ;
0,1,1,1,1,1,2 ; ...
		

Formula

Sum_{k, 0<=k<=n} T(n,k)*x^(n-k)= A166122(n), A166114(n), A084222(n), A084247(n), A000034(n), A040000(n), A000027(n+1), A000079(n), A007051(n), A047849(n), A047850(n), A047851(n), A047852(n), A047853(n), A047854(n), A047855(n), A047856(n) for x= -5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10,11 respectively.
Sum_{k, 0<=k<=n} T(n,k)*x^k= A000007(n), A000027(n+1), A033484(n), A134931(n), A083597(n) for x= 0,1,2,3,4 respectively.
T(n,k)= A166065(n,k)/2^(n-k).
G.f.: (1-x+x*y)/(1-x-x*y+x^2*y). - Philippe Deléham, Nov 09 2013
T(n,k) = T(n-1,k) + T(n-1,k-1) - T(n-2,k-1), T(0,0) = 1, T(1,0) = 0, T(1,1) = 2, T(n,k) = 0 if k<0 or if k>n. - Philippe Deléham, Nov 09 2013

A208324 Triangle T(n,k), read by rows, given by (2, -1/2, 1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (4, -2, 0, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 2, 4, 3, 10, 8, 4, 18, 28, 16, 5, 28, 64, 72, 32, 6, 40, 120, 200, 176, 64, 7, 54, 200, 440, 576, 416, 128, 8, 70, 308, 840, 1456, 1568, 960, 256, 9, 88, 448, 1456, 3136, 4480, 4096, 2176, 512, 10, 108, 624, 2352, 6048, 10752, 13056, 10368, 4864
Offset: 0

Views

Author

Philippe Deléham, Feb 25 2012

Keywords

Comments

Row sums are A134931(n).
Diagonal sums are A140253(n).
Compare this sequence with A207627.
Column k is divisible by 2^k.

Examples

			Triangle begins :
1
2, 4
3, 10, 8
4, 18, 28, 16
5, 28, 64, 72, 32
6, 40, 120, 200, 176, 64
7, 54, 200, 440, 576, 416, 128
8, 70, 308, 840, 1456, 1568, 960, 256
9, 88, 448, 1456, 3136, 4480, 4096, 2176, 512
10, 108, 624, 2352, 6048, 10752, 13056, 10368, 4864, 1024
		

Crossrefs

Formula

T(n,0) = n+1.
T(n,1) = 2*T(n,0) + T(n-1,1).
T(n,k) = 2*T(n-1,k-1) + T(n-1,k) for k>1.
T(n,k) = 2*T(n-1,k) + 2*T(n-1,k-1) - T(n-2,k) - 2*T(n-2,k-1) with T(0,0) = 1, T(1,0) = 2, T(1,1) = 4.
G.f.: (1+2*y*x)/(1-2*(1+y)*x+(1+2*y)*x^2).

A220946 Expansion of (1+2*x+2*x^2-x^3)/((1-x)*(1+x)*(1-3x^2)).

Original entry on oeis.org

1, 2, 6, 7, 21, 22, 66, 67, 201, 202, 606, 607, 1821, 1822, 5466, 5467, 16401, 16402, 49206, 49207, 147621, 147622, 442866, 442867, 1328601, 1328602, 3985806, 3985807, 11957421, 11957422, 35872266, 35872267, 107616801, 107616802, 322850406, 322850407
Offset: 0

Views

Author

Philippe Deléham, Apr 14 2013

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0, 4, 0, -3}, {1, 2, 6, 7}, 40] (* T. D. Noe, Apr 17 2013 *)

Formula

a(n) = a(n-1)+1 if n odd, a(n) = a(n-1)*3 if n even.
a(2n) = A134931(n), a(2n+1) = A060816(n+1).
a(n) = 4*a(n-2) - 3*a(n-4) with a(0)=1, a(1)=2, a(2)=6, a(3)=7.
Previous Showing 11-14 of 14 results.