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.

A165155 a(n) = 100*a(n-1) + 11^(n-1) for n>0, a(0)=0.

Original entry on oeis.org

0, 1, 111, 11221, 1123431, 112357741, 11235935151, 1123595286661, 112359548153271, 11235955029685981, 1123595505326545791, 112359550558592003701, 11235955056144512040711, 1123595505617589632447821, 112359550561793485956926031, 11235955056179728345526186341
Offset: 0

Views

Author

Mark Dols, Sep 05 2009

Keywords

Comments

Generalization of A000225. - Mark Dols, Jan 28 2010

Examples

			From _Mark Dols_, Jan 28 2010: (Start)
As triangle:
  ........... 1
  ......... 1 1 1
  ....... 1 1 2 2 1
  ..... 1 1 2 3 4 3 1
  ... 1 1 2 3 5 7 7 4 1
  . 1 1 2 3 5 9 3 5 1 5 1
  1 1 2 3 5 9 5 2 8 6 6 6 1
(Mirrored version of A162741) (End)
		

Crossrefs

Programs

  • Magma
    [(1/89)*(100^n-11^n): n in [0..40]] // Vincenzo Librandi, Dec 05 2010
    
  • Mathematica
    RecurrenceTable[{a[0]==0,a[n]==100a[n-1]+11^(n-1)},a,{n,40}] (* Harvey P. Dale, Feb 20 2016 *)
  • SageMath
    [(10^(2*n) - 11^n)/89 for n in range(41)] # G. C. Greubel, Feb 09 2023

Formula

G.f.: x/((1-11*x)*(1-100*x)). - R. J. Mathar, Nov 02 2016
E.g.f.: (1/89)*(exp(100*x) - exp(11*x)). - G. C. Greubel, Feb 09 2023

Extensions

a(0) prepended by Bruno Berselli, Oct 02 2015

A165154 a(n) = 100*a(n-1) + (-9)^(n-1) for n>0, a(0)=0.

Original entry on oeis.org

0, 1, 91, 9181, 917371, 91743661, 9174307051, 917431236541, 91743118871131, 9174311930159821, 917431192628561611, 91743119266342945501, 9174311926602913490491, 917431192660573778585581, 91743119266054835992729771, 9174311926605506476065432061
Offset: 0

Views

Author

Mark Dols, Sep 05 2009

Keywords

Crossrefs

Programs

  • Magma
    [(1/109)*(100^n-(-9)^n): n in [0..20]]; // Vincenzo Librandi, Jun 10 2011
    
  • Mathematica
    LinearRecurrence[{91,900}, {0,1}, 40] (* G. C. Greubel, Feb 09 2023 *)
  • PARI
    Vec(x/((1+9*x)*(1-100*x)) + O(x^20)) \\ Colin Barker, Oct 02 2015
    
  • SageMath
    [(100^n-(-9)^n)/109 for n in range(41)] # G. C. Greubel, Feb 09 2023

Formula

From Colin Barker, Oct 02 2015: (Start)
a(n) = 91*a(n-1) + 900*a(n-2) for n>1, a(0)=0.
G.f.: x/((1+9*x)*(1-100*x)). (End)
E.g.f.: (1/109)*(exp(100*x) - exp(-9*x)). - G. C. Greubel, Feb 09 2023

Extensions

a(0) prepended by Joerg Arndt, Oct 02 2015

A164915 Inverse of binomial matrix (10^n,1) A164899. (See A164899 for companion sequence.)

Original entry on oeis.org

1, 1, 10, 1, 9, 100, 1, 8, 90, 1000, 1, 7, 81, 900, 10000, 1, 6, 73, 810, 9000, 100000, 1, 5, 66, 729, 8100, 90000, 1000000, 1, 4, 60, 656, 7290, 81000, 900000, 10000000, 1, 3, 55, 590, 6561, 72900, 810000, 9000000, 100000000
Offset: 1

Views

Author

Mark Dols, Aug 31 2009

Keywords

Comments

Alternate sum and difference of diagonal integers generates A164913.

Examples

			Matrix array, A(n, k), begins:
  1, 10, 100, 1000, 10000, 100000, ...
  1,  9,  90,  900,  9000,  90000, ...
  1,  8,  81,  810,  8100,  81000, ...
  1,  7,  73,  729,  7290,  72900, ...
  1,  6,  66,  656,  6561,  65610, ...
  1,  5,  60,  590,  5905,  59049, ...
  1,  4,  55,  530,  5315,  53144, ...
Antidiagonal triangle, T(n, k), begins as:
  1;
  1, 10;
  1,  9, 100;
  1,  8,  90, 1000;
  1,  7,  81,  900, 10000;
  1,  6,  73,  810,  9000, 100000;
  1,  5,  66,  729,  8100,  90000, 1000000;
		

Crossrefs

Programs

  • Magma
    function T(n,k) // T = A164915
      if k eq n then return 10^(n-1);
      elif k eq 1 then return 1;
      else return T(n-1,k) - T(n-2,k-1);
      end if; return T;
    end function;
    [T(n,k): k in [1..n], n in [1..15]]; // G. C. Greubel, Feb 10 2023
    
  • Mathematica
    T[n_, k_]:= T[n, k]= If[k==n, 10^(n-1), If[k==1, 1, T[n-1,k] - T[n-2, k -1]]];
    Table[T[n, k], {n,15}, {k,n}]//Flatten (* G. C. Greubel, Feb 10 2023 *)
  • SageMath
    def T(n,k): # T = A164915
        if (k==n): return 10^(n-1)
        elif (k==1): return 1
        else: return T(n-1,k) - T(n-2,k-1)
    flatten([[T(n,k) for k in range(1,n+1)] for n in range(1,16)]) # G. C. Greubel, Feb 10 2023

Formula

From G. C. Greubel, Feb 10 2023: (Start)
A(n, k) = A(n-1, k) - A(n-1, k-1), with A(n, 1) = 1 and A(1, k) = 10^(k-1) (array).
T(n, k) = T(n-1, k) - T(n-2, k-1), with T(n, 1) = 1 and T(n, n) = 10^(n-1) (antidiagonal triangle).
Sum_{k=1..n} T(n, k) = (1/273)*(3*10^(n+1) - 15*A057079(n+1) - 12*A128834(n)).
Sum_{k=1..n} (-1)^(k-1)*T(n, k) = (1/109)*(4*Fibonacci(n) + 5*LucasL(n) + (-10)^(n+1)). (End)
Showing 1-3 of 3 results.