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 1-2 of 2 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

A164899 Binomial matrix (1,10^n) read by antidiagonals.

Original entry on oeis.org

1, 1, 10, 1, 11, 100, 1, 12, 110, 1000, 1, 13, 121, 1100, 10000, 1, 14, 133, 1210, 11000, 100000, 1, 15, 146, 1331, 12100, 110000, 1000000, 1, 16, 160, 1464, 13310, 121000, 1100000, 10000000, 1, 17, 175, 1610, 14641, 133100, 1210000, 11000000, 100000000
Offset: 1

Views

Author

Mark Dols, Aug 30 2009

Keywords

Examples

			Matrix array, A(n, k), begins:
  1, 10, 100, 1000, ...
  1, 11, 110, 1100, ...
  1, 12, 121, 1210, ...
  1, 13, 133, 1331, ...
  1, 14, 146, 1464, ...
  1, 15, 160, 1610, ...
Antidiagonal triangle, T(n, k), begins as:
  1;
  1, 10;
  1, 11, 100;
  1, 12, 110, 1000;
  1, 13, 121, 1100, 10000;
  1, 14, 133, 1210, 11000, 100000;
  1, 15, 146, 1331, 12100, 110000, 1000000;
		

Crossrefs

Cf. A094704 (antidiagonal row sums).

Programs

  • Magma
    function T(n,k) // T = A164899
      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 = A164899
        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

Sum_{k=1..n} T(n, k) = A094704(n).
As a triangle T(n,k) read by rows, T(n,1) = 1, T(n,n) = 10^(n-1), and T(n,k) = T(n-1, k) + T(n-2, k-1) otherwise. - Joerg Arndt, Dec 10 2016
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) = A(n-k+1, k) (antidiagonal triangle). (End)
Showing 1-2 of 2 results.