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 1-5 of 5 results.

A094028 Expansion of 1/((1-x)*(1-100*x)).

Original entry on oeis.org

1, 101, 10101, 1010101, 101010101, 10101010101, 1010101010101, 101010101010101, 10101010101010101, 1010101010101010101, 101010101010101010101, 10101010101010101010101, 1010101010101010101010101, 101010101010101010101010101, 10101010101010101010101010101
Offset: 0

Views

Author

Paul Barry, Apr 22 2004

Keywords

Comments

Regarded as binary numbers and converted to decimal, these become 1,5,21,85,... the partial sums of 4^n (see A002450).
Partial sums of 100^n.
Odd terms of A056830. - Alexandre Wajnberg, May 31 2005
101 is the only term that is prime, since (100^k-1)/99 = (10^k+1)/11 * (10^k-1)/9. When k is odd and not 1, (10^k+1)/11 is an integer > 1 and thus (100^k-1)/99 is nonprime. When k is even and greater than 2, (100^k-1)/99 has the prime factor 101 and is nonprime. - Felix Fröhlich, Oct 17 2015
Previous comment is the answer to the problem A1 proposed during the 50th Putnam Competition in 1989 (link). - Bernard Schott, Mar 24 2023

Examples

			From _Omar E. Pol_, Dec 13 2008: (Start)
=======================
n ....... a(n)
0 ........ 1
1 ....... 101
2 ...... 10101
3 ..... 1010101
4 .... 101010101
5 ... 10101010101
======================
(End)
		

References

  • Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 60.
  • Stephen Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

Crossrefs

Bisection of A147759. [Omar E. Pol, Nov 13 2008]
Cf. similar sequences of the form (k^n-1)/(k-1) listed in A269025.

Programs

  • Magma
    [1+100*(100^n-1)/99 : n in [0..15]]; // Wesley Ivan Hurt, Oct 17 2015
    
  • Maple
    A094028:=n->1+100*(100^n-1)/99: seq(A094028(n), n=0..15); # Wesley Ivan Hurt, Oct 17 2015
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-100x)),{x,0,20}],x] (* or *) Table[ FromDigits[ PadRight[{},2n-1,{1,0}]],{n,20}] (* or *) LinearRecurrence[ {101,-100},{1,101},20] (* or *) NestList[100#+1&,1,20] (* Harvey P. Dale, Apr 27 2015 *)
  • Maxima
    A094028(n):=1+100*(100^n-1)/99$
    makelist(A094028(n),n,0,30); /* Martin Ettl, Nov 06 2012 */
    
  • PARI
    a(n) = 1+100*(100^n-1)/99 \\ Felix Fröhlich, Oct 17 2015
    
  • PARI
    Vec(1/((1-x)*(1-100*x)) + O(x^100)) \\ Altug Alkan, Oct 17 2015

Formula

G.f.: 1/((1-x)*(1-100*x)).
a(n) = 1 + 100*(100^n-1)/99. - N. J. A. Sloane, Apr 20 2008
a(n) = 100^(n+1)/99 - 1/99.
a(n) = A094027(2*n+1).
a(n) = 100*a(n-1) + 1, a(0) = 1. - Philippe Deléham, Feb 22 2014
a(n) = 101*a(n-1) - 100*a(n-2) for n > 1. - Wesley Ivan Hurt, Oct 17 2015
a(n) = (100^(n+1) - 1)/99. - Bernard Schott, Apr 15 2021
E.g.f.: exp(x)*(100*exp(99*x) - 1)/99. - Elmo R. Oliveira, Mar 06 2025

A133853 a(n) = (64^n - 1)/63.

Original entry on oeis.org

0, 1, 65, 4161, 266305, 17043521, 1090785345, 69810262081, 4467856773185, 285942833483841, 18300341342965825, 1171221845949812801, 74958198140788019265, 4797324681010433232961, 307028779584667726909505, 19649841893418734522208321, 1257589881178799009421332545
Offset: 0

Views

Author

Paul Curtz, Jan 07 2008

Keywords

Comments

Partial sums of powers of 64 (A089357), a.k.a. q-numbers for q=64.

Crossrefs

Cf. A000364.
Cf. similar sequences of the form (k^n-1)/(k-1) listed in A269025.

Programs

  • Magma
    [(64^n-1)/63: n in [0..20]]; // Vincenzo Librandi, Aug 10 2011
    
  • Mathematica
    LinearRecurrence[{65,-64},{0,1},20] (* Harvey P. Dale, Aug 20 2017 *)
  • Maxima
    makelist((64^n-1)/63, n, 0, 20); /* Martin Ettl, Nov 12 2012 */
  • PARI
    A133853(n)=64^n\63
    

Formula

From Wolfdieter Lang, Apr 08 2022: (Start)
a(n) = Sum_{j=0..n-1} 2^(6*j). See the comment.
G.f.: x/((1 - 64*x)*(1 - x)).
E.g.f.: exp(x)*(exp(63*x) - 1)/63. (End)

Extensions

a(6)-a(15) from Vincenzo Librandi, Aug 10 2011

A218723 a(n) = (256^n - 1)/255.

Original entry on oeis.org

0, 1, 257, 65793, 16843009, 4311810305, 1103823438081, 282578800148737, 72340172838076673, 18519084246547628289, 4740885567116192841985, 1213666705181745367548161, 310698676526526814092329217, 79538861190790864407636279553, 20361948464842461288354887565569
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 256 (A133752), q-integers for q=256.

Crossrefs

Cf. A133752.
Cf. similar sequences of the form (k^n-1)/(k-1) listed in A269025.

Programs

  • Magma
    [n le 2 select n-1 else 257*Self(n-1) - 256*Self(n-2): n in [1..20]]; // Vincenzo Librandi, Nov 07 2012
    
  • Mathematica
    LinearRecurrence[{257, -256}, {0, 1}, 30] (* Vincenzo Librandi, Nov 07 2012 *)
  • PARI
    A218723(n)=256^n\255
    
  • Python
    def A218723(n): return (1<<(n<<3))//255 # Chai Wah Wu, Nov 10 2022

Formula

a(n) = floor(256^n/255).
From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1 - x)*(1 - 256*x)).
a(n) = 257*a(n-1) - 256*a(n-2). (End)
E.g.f.: exp(x)*(exp(255*x) - 1)/255. - Stefano Spezia, Mar 23 2023

A218752 a(n) = (50^n - 1)/49.

Original entry on oeis.org

0, 1, 51, 2551, 127551, 6377551, 318877551, 15943877551, 797193877551, 39859693877551, 1992984693877551, 99649234693877551, 4982461734693877551, 249123086734693877551, 12456154336734693877551, 622807716836734693877551, 31140385841836734693877551
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 50 (A165800).
Converges in a 10-adic sense to ...734693877551.

Crossrefs

Cf. similar sequences of the form (k^n-1)/(k-1) listed in A269025.
Cf. A165800.

Programs

  • Magma
    [n le 2 select n-1 else 51*Self(n-1) - 50*Self(n-2): n in [1..20]]; // Vincenzo Librandi, Nov 08 2012
  • Mathematica
    LinearRecurrence[{51, -50}, {0, 1}, 30] (* Vincenzo Librandi, Nov 08 2012 *)
    (50^Range[0,20]-1)/49 (* Harvey P. Dale, Sep 12 2022 *)
  • Maxima
    makelist(floor(50^n/49), n, 0, 30); /* Martin Ettl, Nov 06 2012 */
    
  • PARI
    a(n)=50^n\49
    

Formula

a(n) = floor(50^n/49).
G.f.: x/((1-x)(1-50x)).
a(0)=0, a(n) = 50*a(n-1) + 1. - Vincenzo Librandi, Nov 08 2012
E.g.f.: exp(x)*(exp(49*x) - 1)/49. - Elmo R. Oliveira, Aug 29 2024

A261544 a(n) = Sum_{k=0..n} 1000^k.

Original entry on oeis.org

1, 1001, 1001001, 1001001001, 1001001001001, 1001001001001001, 1001001001001001001, 1001001001001001001001, 1001001001001001001001001, 1001001001001001001001001001, 1001001001001001001001001001001, 1001001001001001001001001001001001
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 24 2015

Keywords

Comments

A sequence of palindromic numbers.

Examples

			From _Bruno Berselli_, Aug 25 2015: (Start)
a(n)   is the binary representation of    A023001
-------------------------------------------------
1  ...........................................  1
1001  ........................................  9
1001001 .....................................  73
1001001001  ................................  585
1001001001001  ............................  4681
1001001001001001  ........................  37449
1001001001001001001  ....................  299593
1001001001001001001001  ................  2396745
1001001001001001001001001  ............  19173961, etc.
(End)
		

Crossrefs

Subsequence of A033146.
Sums of 100^k: A094028; sums of 10^k: A000042.
Cf. similar sequences of the form (k^n-1)/(k-1) listed in A269025.

Programs

  • Magma
    [(1000^(n+1)-1)/999: n in [0..30]]; // Vincenzo Librandi, Aug 24 2015
  • Mathematica
    Table[(1000^(n + 1) - 1)/999, {n, 0, 15}]
    LinearRecurrence[{1001, -1000}, {1, 1001}, 20] (* Vincenzo Librandi, Aug 24 2015 *)
  • PARI
    Vec(1 / ((x-1)*(1000*x-1)) + O(x^20)) \\ Colin Barker, Aug 24 2015
    

Formula

a(n) = (1000^(n + 1) - 1)/999.
a(n) = 1001*a(n-1) - 1000*a(n-2). - Colin Barker, Aug 24 2015
G.f.: 1 / ((x-1)*(1000*x-1)). - Colin Barker, Aug 24 2015
E.g.f.: (1/999)*(1000000*exp(1000*x) - exp(x)). - G. C. Greubel, Aug 29 2015
Showing 1-5 of 5 results.