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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A102728 Array read by antidiagonals: T(n, k) = ((n+1)^k-(n-1)^k)/2.

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 0, 1, 2, 1, 0, 1, 4, 4, 0, 0, 1, 6, 13, 8, 1, 0, 1, 8, 28, 40, 16, 0, 0, 1, 10, 49, 120, 121, 32, 1, 0, 1, 12, 76, 272, 496, 364, 64, 0, 0, 1, 14, 109, 520, 1441, 2016, 1093, 128, 1, 0, 1, 16, 148, 888, 3376, 7448, 8128, 3280, 256, 0, 0, 1, 18, 193, 1400, 6841
Offset: 0

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Author

Lambert Klasen (lambert.klasen(AT)gmx.net) and Gary W. Adamson, Feb 07 2005

Keywords

Comments

Consider a 2 X 2 matrix M = [N, 1] / [1, N]. The n-th row of the array contains the values of the non-diagonal elements of M^k, k=0,1,.... (Corresponding diagonal entry = non-diagonal entry + (N-1)^k.) Table:
N: row sequence g.f. cross references.
0: (1^n-(-1)^n)/2 x/((1+1x)(1-1x)) A000035
1: (2^n-0^n)/2 x/(1-2x) A000079
2: (3^n-1^n)/2 x/((1-1x)(1-3x)) A003462
3: (4^n-2^n)/2 x/((1-2x)(1-4x)) A006516
4: (7^n-3^n)/2 x/((1-3x)(1-5x)) A005059
5: (6^n-4^n)/2 x/((1-4x)(1-6x)) A016149
6: (7^n-5^n)/2 x/((1-5x)(1-7x)) A016161 A081200
7: (8^n-6^n)/2 x/((1-6x)(1-8x)) A016170 A081201
8: (9^n-7^n)/2 x/((1-7x)(1-9x)) A016178 A081202
9: (10^n-8^n)/2 x/((1-8x)(1-10x)) A016186 A081203
10: (11^n-9^n)/2 x/((1-9x)(1-11x)) A016190
11: (12^n-10^n)/2 x/((1-10x)(1-12x)) A016196
...
Characteristic polynomial x^2-2nx+(n^2-1) has roots n+-1, so if r(n) denotes a row sequence, r(n+1)/r(n) converges to n+1.
Columns follow polynomials with certain binomial coefficients:
column: polynomial
0: 0
1: 1
2: 2n
3: 3n^2+ 1 (see A056107)
4: 4n^3+ 4n (= 8*A006003(n))
5: 5n^4+ 10n^2+ 1
6: 6n^5+ 20n^3+ 6n
7: 7n^6+ 35n^4+ 21n^2+ 1
8; 8n^7+ 56n^5+ 56n^3+ 8n
9: 9n^8+ 84n^6+126n^4+ 36n^2+ 1
10: 10n^9+ 120n^7+252n^5+120n^3+ 10n
11: 11n^10+165n^8+462n^6+330n^4+ 55n^2+ 1

Examples

			Array begins:
0,1,0,1,0,1...
0,1,2,4,8,16...
0,1,4,13,40,121...
0,1,6,28,120,496...
0,1,8,49,272,1441...
...
		

Programs

  • PARI
    MM(n,N)=local(M);M=matrix(n,n);for(i=1,n, for(j=1,n,if(i==j,M[i,j]=N,M[i,j]=1)));M for(k=0,12, for(i=0,k,print1((MM(2,k-i)^i)[1,2],","))) T(n, k) = ((n+1)^k-(n-1)^k)/2 for(k=0,10, for(i=0,10,print1(T(k,i),","));print()) for(k=0,10, for(i=0,10,print1(((k+1)^i-(k-1)^i)/2,","));print()) for(k=0,10, for(i=0,10,print1(polcoeff(x/((1-(k-1)*x)*(1-(k+1)*x)),i),","));print())

A021724 Expansion of 1/((1-x)(1-3x)(1-10x)(1-12x)).

Original entry on oeis.org

1, 26, 465, 7150, 101621, 1378026, 18123145, 233349350, 2958918141, 37094306626, 461004657425, 5690785933950, 69876732453061, 854393804284826, 10411455807073305, 126524771262956950, 1534170271000826381
Offset: 0

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Author

Keywords

Comments

From Bruno Berselli, May 08 2013: (Start)
Naturally, the sequence is related to:
A018207, 1/((1-3x)(1-10x)(1-12x)): A018207(n) = a(n)-a(n-1), n>0;
A016267, 1/((1-x)(1-10x)(1-12x)): A016267(n) = a(n)-3*a(n-1), n>0;
A016217, 1/((1-x)(1-3x)(1-12x)): A016217(n) = a(n)-10*a(n-1), n>0;
A016215, 1/((1-x)(1-3x)(1-10x)): A016215(n) = a(n)-12*a(n-1), n>0;
A016196, 1/((1-10x)(1-12x)): A016196(n) = a(n)-4*a(n-1)+3*a(n-2), n>1;
A016147, 1/((1-3x)(1-12x)): A016147(n) = a(n)-11*a(n-1)+10*a(n-2), n>1;
A016145, 1/((1-3x)(1-10x)): A016145(n) = a(n)-13*a(n-1)+12*a(n-2), n>1;
A016125, 1/((1-x)(1-12x)): A016125(n) = a(n)-13*a(n-1)+30*a(n-2), n>1;
A002275, x/((1-x)(1-10x)): A002275(n) = a(n-1)-15*a(n-2)+36*a(n-3), n>2;
A003462, x/((1-x)(1-3x)): A003462(n) = a(n-1)-22*a(n-2)+120*a(n-3), n>2;
A000012, 1/(1-x): A000012(n) = a(n)-25*a(n-1)+186*a(n-2)-360*a(n-3), n>2;
A000244, 1/(1-3x): A000244(n) = a(n)-23*a(n-1)+142*a(n-2)-120*a(n-3), n>2;
A011557, 1/(1-10x): A011557(n) = a(n)-16*a(n-1)+51*a(n-2)-36*a(n-3), n>2;
A001021, 1/(1-12x): A001021(n) = a(n)-14*a(n-1)+43*a(n-2)-30*a(n-3), n>2. (End)

Crossrefs

Programs

  • Magma
    m:=20; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-3*x)*(1-10*x)*(1-12*x)))); // Bruno Berselli, May 07 2013
  • Mathematica
    CoefficientList[Series[1/((1 - x) (1 - 3 x) (1 - 10 x) (1 - 12 x)), {x, 0, 20}], x] (* Bruno Berselli, May 07 2013 *)
    LinearRecurrence[{26,-211,546,-360},{1,26,465,7150},120] (* Harvey P. Dale, Jul 06 2019 *)
  • PARI
    Vec(1/((1-x)*(1-3*x)*(1-10*x)*(1-12*x))+O(x^20)) \\ Bruno Berselli, May 07 2013
    

Formula

G.f.: 1/((1-x)*(1-3*x)*(1-10*x)*(1-12*x)).
a(n) = -1/198 +3^(n+1)/14 -2^(n+2)*5^(n+3)/63 +2^(2n+5)*3^(n+1)/11. [Bruno Berselli, May 07 2013]
Showing 1-2 of 2 results.