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 1-4 of 4 results.

A145593 Inverse binomial transform of A144472.

Original entry on oeis.org

-1, 3, 4, -7, 24, -47, 104, -207, 424, -847, 1704, -3407, 6824, -13647, 27304, -54607, 109224, -218447, 436904, -873807, 1747624, -3495247, 6990504, -13981007, 27962024, -55924047, 111848104, -223696207, 447392424, -894784847
Offset: 0

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Author

Paul Curtz, Oct 14 2008

Keywords

Comments

From the third entry on, the last digits have period 2.

Programs

  • Mathematica
    LinearRecurrence[{-2,1,2},{-1,3,4},30] (* Harvey P. Dale, May 11 2024 *)

Formula

G.f.: (1-x-11x^2)/((1+2x)(1+x)(x-1)). - R. J. Mathar, Oct 24 2008
a(n)=(5*2^n/3-9/2)*(-1)^n+11/6. - R. J. Mathar, Oct 24 2008

Extensions

Extended by R. J. Mathar, Oct 24 2008

A005015 a(n) = 11*2^n.

Original entry on oeis.org

11, 22, 44, 88, 176, 352, 704, 1408, 2816, 5632, 11264, 22528, 45056, 90112, 180224, 360448, 720896, 1441792, 2883584, 5767168, 11534336, 23068672, 46137344, 92274688, 184549376, 369098752, 738197504, 1476395008, 2952790016, 5905580032, 11811160064
Offset: 0

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Author

Keywords

Comments

The first differences are the sequence itself. - Alexandre Wajnberg & Eric Angelini, Sep 07 2005
11 times powers of 2. - Omar E. Pol, Dec 16 2008
A144472 = -1,2,9,13,31,57,.... a(n) = A144472(n+1)+A144472(n+2). Also a(n) = A144472(n+3)-A144472(n+1). A144472(n+1) is a Jacobsthal sequence from 2 and 9: A144472(n+3) = A144472(n+2)+2*A144472(n+1). Note a(n) mod 9 = period 6: repeat 2,4,8,7,5,1 = A153130(n+1). - Paul Curtz, Jan 06 2009

Crossrefs

Row sums of (10, 1)-Pascal triangle A093645.

Programs

Formula

G.f.: 11/(1-2*x).
a(n) = 2*a(n-1), n>0; a(0)=11. - Philippe Deléham, Nov 23 2008
a(n) = A000079(n)*11. - Omar E. Pol, Dec 16 2008
E.g.f.: 11*exp(2*x). - Elmo R. Oliveira, Aug 16 2024

A053088 a(n) = 3*a(n-2) + 2*a(n-3) for n > 2, a(0)=1, a(1)=0, a(2)=3.

Original entry on oeis.org

1, 0, 3, 2, 9, 12, 31, 54, 117, 224, 459, 906, 1825, 3636, 7287, 14558, 29133, 58248, 116515, 233010, 466041, 932060, 1864143, 3728262, 7456549, 14913072, 29826171, 59652314, 119304657, 238609284, 477218599, 954437166, 1908874365
Offset: 0

Views

Author

Pauline Gorman (pauline(AT)gorman65.freeserve.co.uk), Feb 26 2000

Keywords

Comments

Growth of happy bug population in GCSE math course work assignment.
The generalized (3,2)-Padovan sequence p(3,2;n). See the W. Lang link under A000931. - Wolfdieter Lang, Jun 25 2010
With offset 1: a(n) = -2^n*Sum_{k=0..n} k^p*q^k for p=1, q=-1/2. See also A232603 (p=2, q=-1/2), A232604 (p=3, q=-1/2). - Stanislav Sykora, Nov 27 2013
From Paul Curtz, Nov 02 2021 (Start)
a(n-2) difference table (from 0, 0, a(n)):
0 0 1 0 3 2 9 12 31 54 ...
0 1 -1 3 -1 7 3 19 23 63 ...
1 -2 4 -4 8 -4 16 4 40 44 ...
-3 6 -8 12 -12 20 -12 36 4 84 ...
9 -14 20 -24 32 -32 48 -32 80 0 ...
-23 34 -44 56 -64 80 -80 112 -80 176 ...
57 -78 100 -120 144 -160 192 -192 256 -192 ...
... .
The signature is valid for every row.
a(n-2) + a(n-1) = A001045(n).
a(n-2) + a(n+1) = A062510(n) = 3*A001045(n).
a(n-2) + a(n+3) = see A144472(n+1).
Second subdiagonal: 1, 6, 20, 56, 144, 352, ... = A014480(n).
First subdiagonal: -A036895(n) = -2*A001787(n).
Main diagonal: A001787(n) = -first and -third upper diagonals.
Second, fourth and fifth upper diagonals: A001792(n), A045891(n+2) and A172160(n+1). (End)

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1/(1 - 3 x^2 - 2 x^3), {x, 0, 32}], x] (* Michael De Vlieger, Sep 30 2019 *)
  • PARI
    c(n)=(2^(n+1)-(-1)^n*(3*n+2))/9; a(n)=c(n+1); \\ Stanislav Sykora, Nov 27 2013

Formula

G.f.: 1 / (1-3*x^2-2*x^3).
With offset 1: a(1)=1; a(n) = 2*a(n-1) - (-1)^n*n; a(n) = (1/9)*(2^(n+1) - (-1)^n*(3*n+2)). - Benoit Cloitre, Nov 02 2002
a(n) = Sum_{k=0..floor(n/2)} A078008(n-2k). - Paul Barry, Nov 24 2003
a(n) = Sum_{k=0..floor(n/2)} binomial(k, n-2k)*3^k*(2/3)^(n-2k). - Paul Barry, Oct 16 2004
a(n) = Sum_{k=0..n} A078008(k)*(1 - (-1)^(n+k-1))/2. - Paul Barry, Apr 16 2005
a(n) = ( 2^(n+2) + (-1)^n*(3*n+5) )/9 (see also the B. Cloitre comment above). From the o.g.f. 1/(1-3*x^2-2*x^3) = 1/((1-2*x)*(1+x)^2) = (3/(1+x)^2 + 2/(1+x) + 4/(1-2*x))/9. - Wolfdieter Lang, Jun 25 2010
From Wolfdieter Lang, Aug 26 2010: (Start)
a(n) = a(n-1) + 2*a(n-2) + (-1)^n for n > 1, a(0)=1, a(1)=0.
Due to the identity for the o.g.f. A(x): A(x) = x*(1+2*x)*A(x) + 1/(1+x).
(This recurrence was observed by Gary Detlefs in a 08/25/10 e-mail to the author.) (End)
G.f.: Sum_{n>=0} binomial(3*n,n)*x^n / (1+x)^(3*n+3). - Paul D. Hanna, Mar 03 2012
E.g.f.: 1 + (1/9)*(exp(-x)*(3*x - 2) + 2*exp(2*x)). - Stefano Spezia, Sep 27 2019

Extensions

More terms from James Sellers, Feb 28 2000 and Christian G. Bower, Feb 29 2000

A021069 Decimal expansion of 1/65.

Original entry on oeis.org

0, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5
Offset: 0

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Author

Keywords

Comments

Without the leading 0 also the decimal expansion of 2/13.

Examples

			0.0153846153846...  - _Natan Arie Consigli_, Sep 18 2016
		

Crossrefs

Programs

Formula

Equals 2 - 24/13. See Táfula link. - Michel Marcus, May 31 2024
G.f.: x*(1 + 4*x - 2*x^2 + 6*x^3)/((1 - x)*(1 + x)*(1 - x + x^2)). - Stefano Spezia, Apr 30 2025
Showing 1-4 of 4 results.