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 1-10 of 10 results.

A099669 Partial sums of repdigits of A002276.

Original entry on oeis.org

2, 24, 246, 2468, 24690, 246912, 2469134, 24691356, 246913578, 2469135800, 24691358022, 246913580244, 2469135802466, 24691358024688, 246913580246910, 2469135802469132, 24691358024691354, 246913580246913576, 2469135802469135798, 24691358024691358020, 246913580246913580242
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			2 + 22 + 222 + 2222 = a(4) = 2468.
		

Crossrefs

Programs

  • Maple
    A099669:=n->(2/81)*(10^(n+1) - 9*n - 10): seq(A099669(n), n=1..30); # Wesley Ivan Hurt, Apr 18 2017
  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)
    LinearRecurrence[{12,-21,10},{2,24,246},30] (* Harvey P. Dale, Jun 01 2025 *)

Formula

a(n) = (2/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3). - Matthew House, Jun 30 2016
G.f.: 2*x/((1 - x)^2*(1 - 10*x)). - Ilya Gutkovskiy, Jun 30 2016
From Elmo R. Oliveira, Apr 02 2025: (Start)
E.g.f.: 2*exp(x)*(10*exp(9*x) - 9*x - 10)/81.
a(n) = 2*A014824(n). (End)

A099675 Partial sums of repdigits of A002282.

Original entry on oeis.org

8, 96, 984, 9872, 98760, 987648, 9876536, 98765424, 987654312, 9876543200, 98765432088, 987654320976, 9876543209864, 98765432098752, 987654320987640, 9876543209876528, 98765432098765416, 987654320987654304, 9876543209876543192, 98765432098765432080, 987654320987654320968
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			8 + 88 + 888 + 8888 + 88888 = a(5) = 98760.
		

Crossrefs

Programs

  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)

Formula

a(n) = (8/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3). - Wesley Ivan Hurt, Jan 20 2024
From Elmo R. Oliveira, Apr 02 2025: (Start)
G.f.: 8*x/((1 - x)^2*(1 - 10*x)).
E.g.f.: 8*exp(x)*(10*exp(9*x) - 9*x - 10)/81.
a(n) = 8*A014824(n). (End)

Extensions

More terms from Elmo R. Oliveira, Apr 02 2025

A070189 a(n) = 12345679*n.

Original entry on oeis.org

0, 12345679, 24691358, 37037037, 49382716, 61728395, 74074074, 86419753, 98765432, 111111111, 123456790, 135802469, 148148148, 160493827, 172839506, 185185185, 197530864, 209876543, 222222222, 234567901, 246913580, 259259259, 271604938, 283950617, 296296296, 308641975
Offset: 0

Views

Author

Henry Bottomley, Apr 24 2002

Keywords

Comments

a(82)=1012345678 is the first term which has a digit appearing more than once without an obvious pattern, although a(-82)=-1012345678 might be seen as the concatenation of ten consecutive numbers.

References

  • David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See entry 12345679 at p. 188.

Crossrefs

Programs

  • Mathematica
    Table[12345679*n,{n,0,30}] (* or *) LinearRecurrence[{2,-1},{0,12345679},30] (* Harvey P. Dale, Oct 16 2015 *)
  • PARI
    a(n)=12345679*n \\ Charles R Greathouse IV, Jan 09 2012
    
  • PARI
    concat(0, Vec(12345679*x/(1-x)^2 + O(x^26))) \\ Elmo R. Oliveira, Jun 26 2025

Formula

a(n) = n*(10^(10-1)-1)/(10-1)^2.
From Elmo R. Oliveira, Jun 26 2025: (Start)
G.f.: 12345679*x/(1-x)^2.
E.g.f.: 12345679*x*exp(x).
a(n) = 333667*A085959(n).
a(n) = 2*a(n-1) - a(n-2). (End)

Extensions

More terms from Elmo R. Oliveira, Jun 26 2025

A099674 Partial sums of repdigits of A002281.

Original entry on oeis.org

0, 7, 84, 861, 8638, 86415, 864192, 8641969, 86419746, 864197523, 8641975300, 86419753077, 864197530854, 8641975308631, 86419753086408, 864197530864185, 8641975308641962, 86419753086419739, 864197530864197516, 8641975308641975293, 86419753086419753070, 864197530864197530847
Offset: 0

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			7 + 77 + 777 + 7777 + 77777 = a(5) = 86415.
		

Crossrefs

Programs

  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)
    Accumulate[LinearRecurrence[{11,-10},{0,7},25]] (* Harvey P. Dale, Jul 22 2025 *)

Formula

a(n) = (7/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
From Elmo R. Oliveira, Apr 02 2025: (Start)
G.f.: 7*x/((1 - x)^2*(1 - 10*x)).
E.g.f.: 7*exp(x)*(10*exp(9*x) - 9*x - 10)/81.
a(n) = 7*A014824(n).
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 3. (End)

Extensions

More terms from Elmo R. Oliveira, Apr 02 2025
a(0)=0 prepended by Harvey P. Dale, Jul 22 2025

A099676 Partial sums of repdigits of A002283.

Original entry on oeis.org

9, 108, 1107, 11106, 111105, 1111104, 11111103, 111111102, 1111111101, 11111111100, 111111111099, 1111111111098, 11111111111097, 111111111111096, 1111111111111095, 11111111111111094, 111111111111111093, 1111111111111111092, 11111111111111111091
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Comments

a(n) is the maximal positive integer k such that the sequence 1, 2, 3, 4, ..., k-1, k has a total of n*k digits. - Bui Quang Tuan, Mar 12 2015

Examples

			9 + 99 + 999 + 9999 + 99999 = a(5) = 111105.
		

Crossrefs

Programs

  • Magma
    [(10/9)*(10^n-1)-n: n in [1..20]]; // Vincenzo Librandi, Mar 14 2014
  • Maple
    a:=n->sum((10^(n-j)-1^(n-j)), j=0..n): seq(a(n), n=1..17); # Zerinvary Lajos, Jan 15 2007
  • Mathematica
    <Vincenzo Librandi, Mar 14 2014 *)
    LinearRecurrence[{12,-21,10},{9,108,1107},20] (* Harvey P. Dale, Apr 18 2015 *)
  • PARI
    Vec(-9*x/((x-1)^2*(10*x-1)) + O(x^100)) \\ Colin Barker, Mar 12 2014
    
  • Sage
    [gaussian_binomial(n,1,10)-n for n in range(2,19)] # Zerinvary Lajos, May 29 2009
    

Formula

a(n) = (10/9)*(10^n-1) - n. - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
From Colin Barker, Mar 12 2014: (Start)
a(n) = 12*a(n-1)-21*a(n-2)+10*a(n-3).
G.f.: -9*x / ((x-1)^2*(10*x-1)). (End)
E.g.f.: exp(x)*(10*(exp(9*x) - 1) - 9*x)/9. - Stefano Spezia, Sep 13 2023

A057933 Floor[(80/81)*10^n].

Original entry on oeis.org

9, 98, 987, 9876, 98765, 987654, 9876543, 98765432, 987654320, 9876543209, 98765432098, 987654320987, 9876543209876, 98765432098765, 987654320987654, 9876543209876543, 98765432098765432, 987654320987654320
Offset: 1

Views

Author

Henry Bottomley, Oct 04 2000

Keywords

Crossrefs

Cf. A057932.

Programs

  • Mathematica
    Floor[80/81*10^Range[20]] (* Harvey P. Dale, May 28 2017 *)
  • PARI
    a(n)=10^n*80\81

Formula

G.f.:(9x+8x^2+7x^3+6x^4+5x^5+4x^6+3x^7+2x^8)/((1-10x)(1-x^9)).
a(n)=10*a(n-1)-(n%9)+10*(n%9!=0).

A099672 Partial sums of repdigits of A002279.

Original entry on oeis.org

5, 60, 615, 6170, 61725, 617280, 6172835, 61728390, 617283945, 6172839500, 61728395055, 617283950610, 6172839506165, 61728395061720, 617283950617275, 6172839506172830, 61728395061728385, 617283950617283940, 6172839506172839495, 61728395061728395050, 617283950617283950605
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			5 + 55 + 555 + 5555 + 55555 = a(5) = 61725.
		

Crossrefs

Programs

  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)
    Accumulate[Table[FromDigits[PadRight[{},n,5]],{n,0,20}]] (* Harvey P. Dale, Oct 05 2013 *)
  • PARI
    Vec(5*x/((1 - x)^2*(1 - 10*x)) + O(x^40)) \\ Colin Barker, Nov 30 2017

Formula

a(n) = (5/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004.
From Colin Barker, Nov 30 2017: (Start)
G.f.: 5*x/((1 - x)^2*(1 - 10*x)).
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 3. (End)
From Elmo R. Oliveira, Apr 03 2025: (Start)
E.g.f.: 5*exp(x)*(10*exp(9*x) - 9*x - 10)/81.
a(n) = 5*A014824(n). (End)

A099670 Partial sums of repdigits of A002277.

Original entry on oeis.org

3, 36, 369, 3702, 37035, 370368, 3703701, 37037034, 370370367, 3703703700, 37037037033, 370370370366, 3703703703699, 37037037037032, 370370370370365, 3703703703703698, 37037037037037031, 370370370370370364, 3703703703703703697, 37037037037037037030, 370370370370370370363
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			3 + 33 + 333 + 3333 = a(4) = 3702.
		

Crossrefs

Programs

  • Maple
    a:=n->sum((10^(n-j)-1^(n-j))/3,j=0..n): seq(a(n), n=1..18); # Zerinvary Lajos, Jan 15 2007
  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)

Formula

a(n) = (3/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
From Elmo R. Oliveira, Apr 02 2025: (Start)
G.f.: 3*x/((1 - x)^2*(1 - 10*x)).
E.g.f.: 3*exp(x)*(10*exp(9*x) - 9*x - 10)/81.
a(n) = 3*A014824(n).
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 3. (End)

Extensions

More terms from Elmo R. Oliveira, Apr 02 2025

A099671 Partial sums of repdigits of A002278.

Original entry on oeis.org

4, 48, 492, 4936, 49380, 493824, 4938268, 49382712, 493827156, 4938271600, 49382716044, 493827160488, 4938271604932, 49382716049376, 493827160493820, 4938271604938264, 49382716049382708, 493827160493827152, 4938271604938271596, 49382716049382716040, 493827160493827160484
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			4 + 44 + 444 + 4444 + 44444 = a(5) = 49380.
		

Crossrefs

Programs

  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)

Formula

a(n) = (4/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
From Chai Wah Wu, Feb 28 2018: (Start)
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 3.
G.f.: 4*x/((1 - x)^2*(1 - 10*x)). (End)
From Elmo R. Oliveira, Apr 03 2025: (Start)
E.g.f.: 4*exp(x)*(10*exp(9*x) - 9*x - 10)/81.
a(n) = 4*A014824(n). (End)

Extensions

More terms from Elmo R. Oliveira, Apr 03 2025

A099673 Partial sums of repdigits of A002280.

Original entry on oeis.org

6, 72, 738, 7404, 74070, 740736, 7407402, 74074068, 740740734, 7407407400, 74074074066, 740740740732, 7407407407398, 74074074074064, 740740740740730, 7407407407407396, 74074074074074062, 740740740740740728, 7407407407407407394, 74074074074074074060, 740740740740740740726
Offset: 1

Views

Author

Labos Elemer, Nov 17 2004

Keywords

Examples

			6 + 66 + 666 + 6666 + 66666 = a(5) = 74070.
		

Crossrefs

Programs

  • Mathematica
    <Robert G. Wilson v, Nov 20 2004 *)

Formula

a(n) = (2/27)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004
From Elmo R. Oliveira, Apr 02 2025: (Start)
G.f.: 6*x/((1 - x)^2*(1 - 10*x)).
a(n) = 6*A014824(n).
E.g.f.: 2*exp(x)*(10*exp(9*x) - 9*x - 10)/27.
a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 3. (End)

Extensions

More terms from Elmo R. Oliveira, Apr 02 2025
Showing 1-10 of 10 results.