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 11-13 of 13 results.

A115634 Expansion of (1-4*x^2)/(1-x^2).

Original entry on oeis.org

1, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0
Offset: 0

Views

Author

Paul Barry, Jan 27 2006

Keywords

Comments

Row sums of number triangle A115633.

Crossrefs

Programs

  • Magma
    [4*0^n -3*(1+(-1)^n)/2: n in [0..100]]; // G. C. Greubel, Nov 23 2021
    
  • Mathematica
    Join[{1}, -3*Mod[Range[100] -1, 2]] (* G. C. Greubel, Nov 23 2021 *)
    CoefficientList[Series[(1-4x^2)/(1-x^2),{x,0,100}],x] (* or *) LinearRecurrence[{0,1},{1,0,-3},100] (* or *) PadRight[{1},100,{-3,0}] (* Harvey P. Dale, Dec 06 2024 *)
  • Sage
    [1]+[-3*((n-1)%2) for n in (1..100)] # G. C. Greubel, Nov 23 2021

Formula

a(n) = 4*0^n - 3*(1 + (-1)^n)/2.
a(n) = Sum_{k=0..n} A115633(n, k).
From G. C. Greubel, Nov 23 2021: (Start)
a(n) = 1 if n = 0, otherwise a(n) = -A010674(n-1).
E.g.f.: 4 - 3*cosh(x). (End)

A160019 Triangle: Lodumo_2 applied to each row of Pascal's triangle .

Original entry on oeis.org

1, 1, 3, 1, 0, 3, 1, 3, 5, 7, 1, 0, 2, 4, 3, 1, 3, 0, 2, 5, 7, 1, 0, 3, 2, 5, 4, 7, 1, 3, 5, 7, 9, 11, 13, 15, 1, 0, 2, 4, 6, 8, 10, 12, 3, 1, 3, 0, 2, 4, 6, 8, 10, 5, 7, 1, 0, 3, 2, 4, 6, 8, 10, 5, 12, 7, 1, 3, 5, 7, 0, 2, 4, 6, 9, 11, 13, 15, 1, 0, 2, 4, 3, 6, 8, 10, 5, 12, 14, 16, 7
Offset: 0

Views

Author

Philippe Deléham, Apr 29 2009, May 02 2009

Keywords

Examples

			Triangle begins:
  1;
  1, 3;
  1, 0, 3;
  1, 3, 5, 7;
  1, 0, 2, 4, 3;
  1, 3, 0, 2, 5, 7; ...
		

Crossrefs

Row sums are A160020.

Programs

  • PARI
    \\ here S(n,k) is A047999.
    S(n,k)={bitand(n-k, k)==0}
    row(n)={my(v=vector(n+1), b=0); for(k=0, n, if(S(n,k), b++; v[1+k]=2*b-1, v[1+k]=2*(k-b))); v}
    { for(n=0, 10, print(row(n))) } \\ Andrew Howroyd, Feb 02 2020

Formula

T(n,0)=A000012(n)=1; T(n,1)=A010674(n). - Philippe Deléham, Nov 15 2011

A174971 Periodic sequence: Repeat 3, -3.

Original entry on oeis.org

3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3, 3, -3
Offset: 0

Views

Author

Klaus Brockhaus, Apr 04 2010

Keywords

Comments

Interleaving of A010701 and -A010701; signed version of A010701.
Essentially first differences of A010674.
Inverse binomial transform of 3 followed by A000004.
Second inverse binomial transform of A010701.
Third inverse binomial transform of A007283.
Fourth inverse binomial transform of A000244 without initial term 1.
Fifth inverse binomial transform of A164346.
Sixth inverse binomial transform of A005053 without initial term 1.
Seventh inverse binomial transform of A169604.
Eighth inverse binomial transform of A169634.
Ninth inverse binomial transform of A103333 without initial term 1.
Tenth inverse binomial transform of A013708.
Eleventh inverse binomial transform of A093138 without initial term 1.

Crossrefs

Cf. A010701 (all 3's sequence), A000004 (all zeros sequence), A007283 (3*2^n), A000244 (powers of 3), A164346 (3*4^n), A005053 (expand (1-2x)/(1-5x)), A169604 (3*6^n), A169634 (3*7^n), A103333 (expand (1-5x)/(1-8x)), A013708 (3^(2n+1)), A093138 (expand (1-7x)/(1-10x)).

Programs

  • Magma
    &cat[ [3, -3]: n in [0..41] ];
    [ 3*(-1)^n: n in [0..83] ];
    
  • Mathematica
    PadRight[{},120,{3,-3}] (* or *) NestList[-1#&,3,120] (* Harvey P. Dale, Dec 30 2023 *)
  • PARI
    a(n)=3*(-1)^n \\ Charles R Greathouse IV, Jun 13 2013

Formula

a(n) = 3*(-1)^n.
a(n) = -a(n-1) for n > 0; a(0) = 3.
a(n) = a(n-2) for n > 1; a(0) = 3, a(1) = -3.
G.f.: 3/(1+x).
Previous Showing 11-13 of 13 results.