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 1-3 of 3 results.

A152776 Numbers such that every run length in base 2 is 3.

Original entry on oeis.org

7, 56, 455, 3640, 29127, 233016, 1864135, 14913080, 119304647, 954437176, 7635497415, 61083979320, 488671834567, 3909374676536, 31274997412295, 250199979298360, 2001599834386887, 16012798675095096, 128102389400760775
Offset: 1

Views

Author

Omar E. Pol, Jan 18 2009

Keywords

Comments

a(n) is the number whose binary representation is A152775(n).

Crossrefs

Formula

a(n)= 8*a(n-1) +a(n-2) -8*a(n-3). G.f.: 7x/((1-x)(1-8x)(1+x)). a(n)= (-7*(-1)^n-9+16*8^n)/18 = 7*A033118(n). [From R. J. Mathar, Jan 20 2009]

Extensions

More terms from R. J. Mathar, Jan 20 2009

A154805 Numbers with 4n binary digits where every run length is 4, written in binary.

Original entry on oeis.org

1111, 11110000, 111100001111, 1111000011110000, 11110000111100001111, 111100001111000011110000, 1111000011110000111100001111, 11110000111100001111000011110000, 111100001111000011110000111100001111
Offset: 1

Views

Author

Omar E. Pol, Jan 25 2009

Keywords

Comments

A154806 written in base 2.

Examples

			n ... a(n) ................... A154806(n)
1 ... 1111 ................... 15
2 ... 11110000 ............... 240
3 ... 111100001111 ........... 3855
4 ... 1111000011110000 ....... 61680
5 ... 11110000111100001111 ... 986895
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1111/((x - 1) (x + 1) (10000 x - 1)), {x, 0, 10}], x] (* Vincenzo Librandi, Apr 22 2014 *)
    LinearRecurrence[{10000,1,-10000},{1111,11110000,111100001111},20] (* Harvey P. Dale, Jul 31 2017 *)
  • PARI
    Vec(1111*x/((x-1)*(x+1)*(10000*x-1)) + O(x^100)) \\ Colin Barker, Apr 20 2014

Formula

From Colin Barker, Apr 20 2014: (Start)
a(n) = (-10001-9999*(-1)^n+2^(5+4*n)*625^(1+n))/180018.
a(n) = 10000*a(n-1)+a(n-2)-10000*a(n-3).
G.f.: 1111*x / ((x-1)*(x+1)*(10000*x-1)). (End)

A154807 Numbers with 5n binary digits where every run length is 5, written in binary.

Original entry on oeis.org

11111, 1111100000, 111110000011111, 11111000001111100000, 1111100000111110000011111, 111110000011111000001111100000, 11111000001111100000111110000011111, 1111100000111110000011111000001111100000, 111110000011111000001111100000111110000011111
Offset: 1

Views

Author

Omar E. Pol, Jan 25 2009

Keywords

Comments

A154808 written in base 2.

Examples

			n ... a(n) ........................ A154808(n)
1 ... 11111 ....................... 31
2 ... 1111100000 .................. 992
3 ... 111110000011111 ............. 31775
4 ... 11111000001111100000 ........ 1016800
5 ... 1111100000111110000011111 ... 32537631
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[11111/((x - 1) (x + 1) (100000 x - 1)), {x, 0, 10}], x] (* Vincenzo Librandi, Apr 22 2014 *)
    LinearRecurrence[{100000,1,-100000},{11111,1111100000,111110000011111},20] (* Harvey P. Dale, Aug 08 2023 *)
  • PARI
    Vec(11111*x/((x-1)*(x+1)*(100000*x-1)) + O(x^100)) \\ Colin Barker, Apr 20 2014

Formula

From Colin Barker, Apr 20 2014: (Start)
a(n) = (-100001-99999*(-1)^n+2^(6+5*n)*3125^(1+n))/1800018.
a(n) = 100000*a(n-1)+a(n-2)-100000*a(n-3).
G.f.: 11111*x / ((x-1)*(x+1)*(100000*x-1)). (End)

Extensions

More terms from Colin Barker, Apr 20 2014
Showing 1-3 of 3 results.