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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A033008 Every run of digits of n in base 10 has length 2.

Original entry on oeis.org

11, 22, 33, 44, 55, 66, 77, 88, 99, 1100, 1122, 1133, 1144, 1155, 1166, 1177, 1188, 1199, 2200, 2211, 2233, 2244, 2255, 2266, 2277, 2288, 2299, 3300, 3311, 3322, 3344, 3355, 3366, 3377, 3388, 3399, 4400, 4411, 4422, 4433
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014

Programs

  • Mathematica
    Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 10]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)

Formula

a(n) = 11*A043314(n) (= 11*n for n<10). - M. F. Hasler, Feb 02 2014

A152775 Numbers with 3n binary digits where every run length is 3, written in binary.

Original entry on oeis.org

111, 111000, 111000111, 111000111000, 111000111000111, 111000111000111000, 111000111000111000111, 111000111000111000111000, 111000111000111000111000111, 111000111000111000111000111000
Offset: 1

Views

Author

Omar E. Pol, Jan 18 2009

Keywords

Comments

A152776 written in base 2.

Examples

			n ... a(n) .............. A152776(n)
1 ... 111 ............... 7
2 ... 111000 ............ 56
3 ... 111000111 ......... 455
4 ... 111000111000 ...... 3640
5 ... 111000111000111 ... 29127
		

Crossrefs

Programs

  • Mathematica
    FromDigits/@Table[Flatten[PadRight[{},n,{a,b}]/.{a->{1,1,1},b->{0,0,0}}],{n,10}] (* Harvey P. Dale, Mar 23 2012 *)
    CoefficientList[Series[111/((x - 1) (x + 1) (1000 x - 1)), {x, 0, 20}], x] (* Vincenzo Librandi, Apr 21 2014 *)
  • PARI
    Vec(111*x / ((x-1)*(x+1)*(1000*x-1)) + O(x^100)) \\ Colin Barker, Apr 20 2014

Formula

From Colin Barker, Apr 20 2014: (Start)
a(n) = (-1001-999*(-1)^n+2^(4+3*n)*125^(1+n))/18018.
a(n) = 1000*a(n-1)+a(n-2)-1000*a(n-3).
G.f.: 111*x / ((x-1)*(x+1)*(1000*x-1)). (End).

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

A033003 Every run of digits of n in base 5 has length 2.

Original entry on oeis.org

6, 12, 18, 24, 150, 162, 168, 174, 300, 306, 318, 324, 450, 456, 462, 474, 600, 606, 612, 618, 3756, 3762, 3768, 3774, 4050, 4056, 4068, 4074, 4200, 4206, 4212, 4224, 4350, 4356, 4362, 4368, 7506, 7512, 7518, 7524, 7650, 7662
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014

Programs

  • Mathematica
    Select[Range[10000],Union[Length/@Split[IntegerDigits[#, 5]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)

Formula

a(n) = 6*A043309(n) (= 6*n for n<5). - M. F. Hasler, Feb 02 2014

A033007 Every run of digits of n in base 9 has length 2.

Original entry on oeis.org

10, 20, 30, 40, 50, 60, 70, 80, 810, 830, 840, 850, 860, 870, 880, 890, 1620, 1630, 1650, 1660, 1670, 1680, 1690, 1700, 2430, 2440, 2450, 2470, 2480, 2490, 2500, 2510, 3240, 3250, 3260, 3270, 3290, 3300, 3310, 3320, 4050
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014

Programs

  • Mathematica
    Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 9]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)

Formula

a(n) = 10*A043313(n) (= 10*n for n<9). - M. F. Hasler, Feb 02 2014

A033010 Numbers each of whose runs of digits in base 12 has length 2.

Original entry on oeis.org

13, 26, 39, 52, 65, 78, 91, 104, 117, 130, 143, 1872, 1898, 1911, 1924, 1937, 1950, 1963, 1976, 1989, 2002, 2015, 3744, 3757, 3783, 3796, 3809, 3822, 3835, 3848, 3861, 3874, 3887, 5616, 5629, 5642, 5668, 5681, 5694, 5707, 5720, 5733, 5746, 5759, 7488, 7501
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014
Numbers without repeating adjacent digits for which all digits are divisible by 13, in base 144. Consequently there are 11^n n-digit members of this sequence (base 144) and so (11^(n+1)-1)/10 members of this sequence below 144^n. - Charles R Greathouse IV, Feb 02 2014

Programs

  • Mathematica
    Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 12]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)
  • Python
    from sympy.ntheory import digits
    from itertools import groupby
    def ok(n):
      return all(len(list(g))==2 for k, g in groupby(digits(n, 12)[1:]))
    print(list(filter(ok, range(1, 7502)))) # Michael S. Branicky, Apr 27 2021

Formula

a(n) = 13*A043316(n) (= 13*n for n < 12). - M. F. Hasler, Feb 02 2014

A154808 Numbers such that every run length in base 2 is 5.

Original entry on oeis.org

31, 992, 31775, 1016800, 32537631, 1041204192, 33318534175, 1066193093600, 34118178995231, 1091781727847392, 34937015291116575, 1117984489315730400, 35775503658103372831, 1144816117059307930592, 36634115745897853778975
Offset: 1

Views

Author

Omar E. Pol, Jan 25 2009

Keywords

Comments

a(n) is the number whose binary representation is A154807(n).

Crossrefs

Programs

  • Mathematica
    FromDigits[#,2]&/@Table[PadRight[{},5n,{1,1,1,1,1,0,0,0,0,0}],{n,20}] (* or *) LinearRecurrence[{32,1,-32},{31,992,31775},20] (* Harvey P. Dale, May 08 2016 *)

Formula

Conjecture: a(n) = (-33-31*(-1)^n+2^(6+5*n))/66. g.f.: 31*x / ((x-1)*(x+1)*(32*x-1)). - Colin Barker, Sep 16 2013

Extensions

More terms from Sean A. Irvine, Feb 21 2010

A033004 Every run of digits of n in base 6 has length 2.

Original entry on oeis.org

7, 14, 21, 28, 35, 252, 266, 273, 280, 287, 504, 511, 525, 532, 539, 756, 763, 770, 784, 791, 1008, 1015, 1022, 1029, 1043, 1260, 1267, 1274, 1281, 1288, 9079, 9086, 9093, 9100, 9107, 9576, 9583, 9597, 9604, 9611, 9828, 9835
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014

Crossrefs

Programs

  • Mathematica
    Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 6]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)

Formula

a(n) = 7*A043310(n) (= 7*n for n<6). - M. F. Hasler, Feb 02 2014

A033005 Every run of digits of n in base 7 has length 2.

Original entry on oeis.org

8, 16, 24, 32, 40, 48, 392, 408, 416, 424, 432, 440, 784, 792, 808, 816, 824, 832, 1176, 1184, 1192, 1208, 1216, 1224, 1568, 1576, 1584, 1592, 1608, 1616, 1960, 1968, 1976, 1984, 1992, 2008, 2352, 2360, 2368, 2376, 2384, 2392
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014

Programs

  • Mathematica
    Select[Range[2500],Union[Length/@Split[IntegerDigits[#,7]]]=={2}&] (* Harvey P. Dale, Oct 24 2011 *)

Formula

a(n) = 8*A043311(n) (= 8*n for n<7). - M. F. Hasler, Feb 02 2014

A033006 Every run of digits of n in base 8 has length 2.

Original entry on oeis.org

9, 18, 27, 36, 45, 54, 63, 576, 594, 603, 612, 621, 630, 639, 1152, 1161, 1179, 1188, 1197, 1206, 1215, 1728, 1737, 1746, 1764, 1773, 1782, 1791, 2304, 2313, 2322, 2331, 2349, 2358, 2367, 2880, 2889, 2898, 2907, 2916, 2934
Offset: 1

Views

Author

Keywords

Comments

See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - M. F. Hasler, Feb 02 2014

Programs

  • Mathematica
    Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 8]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)

Formula

a(n) = 9*A043312(n) (= 9*n for n<8). - M. F. Hasler, Feb 02 2014

Extensions

Typo in name corrected by Vincenzo Librandi, Feb 05 2014
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