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 1-5 of 5 results.

A093847 First column of triangle A093846.

Original entry on oeis.org

9, 54, 399, 3249, 27999, 249999, 2285713, 21249999, 199999999, 1899999999, 18181818180, 174999999999, 1692307692306, 16428571428570, 159999999999999, 1562499999999999, 15294117647058822, 149999999999999999
Offset: 1

Views

Author

Amarnath Murthy, Apr 18 2004

Keywords

Crossrefs

Cf. A093846.

Programs

  • Magma
    [10^(n-1) -1 +Floor(9*10^(n-1)/n): n in [1..20]]; // G. C. Greubel, Mar 22 2019
    
  • Maple
    A093847 := proc(n) RETURN (10^(n-1)-1+floor(9*(10^(n-1)/n))); end; for n from 1 to 20 do printf("%d,",A093847(n)); od; # R. J. Mathar, Jun 23 2006
  • Mathematica
    Table[10^(n-1)-1+Floor[9 10^(n-1)/n],{n,20}] (* Harvey P. Dale, Oct 21 2011 *)
  • PARI
    {a(n) = 10^(n-1) -1 +floor(9*10^(n-1)/n)}; \\ G. C. Greubel, Mar 22 2019
    
  • Sage
    [10^(n-1) -1 +floor(9*10^(n-1)/n) for n in (1..20)] # G. C. Greubel, Mar 22 2019

Formula

a(n) = 10^(n-1) - 1 + floor(9*10^(n-1)/n) = A093846(n, 1). - R. J. Mathar, Jun 23 2006

Extensions

More terms from R. J. Mathar, Jun 23 2006
Edited by David Wasserman, Mar 26 2007

A093849 Row sums of triangle A093846.

Original entry on oeis.org

9, 153, 2097, 26496, 319995, 3749994, 42999985, 484999992, 5399999991, 59499999990, 649999999935, 7049999999988, 75999999999924, 814999999999941, 8699999999999985, 92499999999999984, 979999999999999902
Offset: 1

Views

Author

Amarnath Murthy, Apr 18 2004

Keywords

Crossrefs

Cf. A093846.

Programs

  • Magma
    [n*(2*10^(n-1) -2 +(n+1)*Floor(9*10^(n-1)/n))/2: n in [1..20]]; // G. C. Greubel, Mar 22 2019
    
  • Mathematica
    Table[n*(2*10^(n-1) -2 +(n+1)*Floor[9*10^(n-1)/n])/2, {n, 1, 20}] (* G. C. Greubel, Mar 22 2019 *)
  • PARI
    {a(n) = n*(2*10^(n-1) -2 +(n+1)*floor(9*10^(n-1)/n))/2}; \\ G. C. Greubel, Mar 22 2019
    
  • Sage
    [n*(2*10^(n-1) -2 +(n+1)*floor(9*10^(n-1)/n))/2 for n in (1..20)] # G. C. Greubel, Mar 22 2019

Formula

a(n) = n*(2*10^(n-1) - 2 + (n+1)*floor(9*10^(n-1)/n))/2.

Extensions

Edited and extended by David Wasserman, Mar 26 2007

A093850 Triangle T(n,k) = 10^(n-1) -1 + k*floor(9*10^(n-1)/(n+1)), with 1 <= r <= n, read by rows.

Original entry on oeis.org

4, 39, 69, 324, 549, 774, 2799, 4599, 6399, 8199, 24999, 39999, 54999, 69999, 84999, 228570, 357141, 485712, 614283, 742854, 871425, 2124999, 3249999, 4374999, 5499999, 6624999, 7749999, 8874999, 19999999, 29999999, 39999999, 49999999, 59999999, 69999999, 79999999, 89999999
Offset: 1

Views

Author

Amarnath Murthy, Apr 18 2004

Keywords

Comments

The n-th row of this triangle contains n uniformly located n-digit numbers, i.e., n terms of an arithmetic progression with 10^(n-1)-1 as the term preceding the first term and (n+1)-th term is the largest possible n-digit term.
Starting with n=2, the n-th row of this triangle can be obtained by deleting the least significant digit, 9, from terms ending in 9 in the (n+1)-th row, and ignoring the main diagonal terms, of the triangle in A093846.
Floor(A093846(4,1)/10) = T(3,1) = 324, but floor(A093846(2,1)/10) = 5 and T(1,1) = 4, floor(A093846(7,1)/10) = 228571 and T(6,1) = 228570, etc. - Michael De Vlieger, Jul 18 2016

Examples

			Triangle begins with:
      4;
     39,    69;
    324,   549,   774;
   2799,  4599,  6399,  8199;
  24999, 39999, 54999, 69999, 84999;
  ....
		

Crossrefs

Programs

  • Magma
    [[10^(n-1) -1 +k*Floor(9*10^(n-1)/(n+1)): k in [1..n]]: n in [1..8]]; // G. C. Greubel, Mar 21 2019
    
  • Maple
    A093850 := proc(n,r)
            10^(n-1)-1+r*floor(9*10^(n-1)/(n+1)) ;
    end proc:
    seq(seq(A093850(n,r),r=1..n),n=1..14) ; # R. J. Mathar, Sep 28 2011
  • Mathematica
    Table[# -1 +r*Floor[9*#/(n+1)] &[10^(n-1)], {n, 8}, {r, n}]//Flatten (* Michael De Vlieger, Jul 18 2016 *)
  • PARI
    {T(n,k) = 10^(n-1) -1 +k*floor(9*10^(n-1)/(n+1))}; \\ G. C. Greubel, Mar 21 2019
    
  • Sage
    [[10^(n-1) -1 +k*floor(9*10^(n-1)/(n+1)) for k in (1..n)] for n in (1..8)] # G. C. Greubel, Mar 21 2019

Extensions

Second comment clarified by Michael De Vlieger, Jul 18 2016
Edited by G. C. Greubel, Mar 21 2019

A093852 a(n) = 10^(n-1) - 1 + n*floor(9*10^(n-1)/(n+1)).

Original entry on oeis.org

4, 69, 774, 8199, 84999, 871425, 8874999, 89999999, 909999999, 9181818179, 92499999999, 930769230759, 9357142857140, 93999999999999, 943749999999999, 9470588235294111, 94999999999999999, 952631578947368403, 9549999999999999999, 95714285714285714279
Offset: 1

Views

Author

Amarnath Murthy, Apr 18 2004

Keywords

Comments

This sequence is the main diagonal of A093850.

Examples

			n-th row of the following triangle contains n uniformly located n-digit numbers. i.e. n terms of an arithmetic progression with 10^(n-1)-1 as the term preceding the first term and (n+1)-th term is the largest possible n-digit term.
Given the triangle defined in A093850:
...4;
..39   69;
.324  549  774;
2799 4599 6399 8199.....
then this sequence is the leading diagonal.
		

Crossrefs

Programs

  • Magma
    [10^(n-1) -1 +n*Floor(9*10^(n-1)/(n+1)): n in [1..25]]; // G. C. Greubel, Mar 21 2019
    
  • Maple
    A093852 := proc(n)
            r := n ;
            10^(n-1)-1+r*floor(9*10^(n-1)/(n+1)) ;
    end proc:
    seq(A093852(n),n=1..50) ; # R. J. Mathar, Oct 01 2011
  • Mathematica
    Table[10^(n-1) -1 +n*Floor[9*10^(n-1)/(n+1)], {n,25}] (* G. C. Greubel, Mar 21 2019 *)
  • PARI
    {a(n) = 10^(n-1) -1 +n*floor(9*10^(n-1)/(n+1))}; \\ G. C. Greubel, Mar 21 2019
    
  • Sage
    [10^(n-1) -1 +n*floor(9*10^(n-1)/(n+1)) for n in (1..25)] # G. C. Greubel, Mar 21 2019

A093851 a(n) = A002283(n-1) + floor(A052268(n)/(1+n)).

Original entry on oeis.org

4, 39, 324, 2799, 24999, 228570, 2124999, 19999999, 189999999, 1818181817, 17499999999, 169230769229, 1642857142856, 15999999999999, 156249999999999, 1529411764705881, 14999999999999999, 147368421052631577, 1449999999999999999, 14285714285714285713
Offset: 1

Views

Author

Amarnath Murthy, Apr 18 2004

Keywords

Comments

The first column r=1 of a triangle defined by T(n,r) = 10^(n-1) -1 + r*floor(9*10^(n-1)/(n+1)).
A row starts with a (virtual) 0th column of a rep-9-digit and fills the remainder with n+1 numbers in arithmetic progression with the largest step such that all numbers in the n-th row are n-digit numbers.

Examples

			The triangle starts in row n=1 as
4 9 # -1, -1+5, -1+2*5
39 69 99 # 9,9+30,9+2*30
324 549 774 999 # 99, 99+225, 99+2*225, 99+3*225
2799 4599 6399 8199 9999 # 999, 999+1800, 999+2*1800,..
...
The sequence contains the first column.
		

Crossrefs

Programs

  • Magma
    [10^(n-1) -1 +Floor(9*10^(n-1)/(n+1)): n in [1..20]]; // G. C. Greubel, Apr 02 2019
    
  • Maple
    A093851 := proc(n) 10^(n-1)-1+floor(9*10^(n-1)/(n+1)) ; end proc: seq(A093851(n),n=1..20) ; # R. J. Mathar, Oct 14 2010
  • Mathematica
    Table[10^(n-1) -1 +Floor[9*10^(n-1)/(n+1)], {n, 1, 20}] (* G. C. Greubel, Apr 02 2019 *)
  • PARI
    {a(n) = 10^(n-1) -1 +floor(9*10^(n-1)/(n+1))}; \\ G. C. Greubel, Apr 02 2019
    
  • Sage
    [10^(n-1) -1 +floor(9*10^(n-1)/(n+1)) for n in (1..20)] # G. C. Greubel, Apr 02 2019

Formula

a(n) = 10^(n-1) -1 + floor(9*10^(n-1)/(n+1)). - G. C. Greubel, Apr 02 2019

Extensions

More terms from R. J. Mathar, Oct 14 2010
Showing 1-5 of 5 results.