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.

A113705 Inverse Moebius transform of powers of 10.

Original entry on oeis.org

1, 10, 110, 1010, 10110, 100010, 1001110, 10000010, 100010110, 1000001010, 10000100110, 100000000010, 1000001011110, 10000000000010, 100000010000110, 1000000000101010, 10000000100010110, 100000000000000010, 1000000001001001110, 10000000000000000010, 100000000010000110110
Offset: 0

Views

Author

Paul Barry, Nov 05 2005

Keywords

Comments

A055895 to base 2.
The triangle formed by stacking the reversals of a(n) is A113704.
Using decimal positional notation, write a 1 at position d for all divisors d of n. All other digits are zeros and leading zeros are not permitted. - Michael De Vlieger, May 24 2017

Examples

			From _Michael De Vlieger_, May 24 2017: (Start)
First 20 terms of a(n), replacing zeros with "." to more clearly show positions of 1s in positions corresponding to terms in row n of A027750. This chart also pertains to terms of A055895 written in binary.
   n                    a(n)  A027750(n)
   ---------------------------------------
   0:                      1  {}
   1:                     1.  1
   2:                    11.  1,2
   3:                   1.1.  1,3
   4:                  1.11.  1,2,4
   5:                 1...1.  1,5
   6:                1..111.  1,2,3,6
   7:               1.....1.  1,7
   8:              1...1.11.  1,2,4,8
   9:             1.....1.1.  1,3,9
  10:            1....1..11.  1,2,5,10
  11:           1.........1.  1,11
  12:          1.....1.1111.  1,2,3,4,6,12
  13:         1...........1.  1,13
  14:        1......1....11.  1,2,7,14
  15:       1.........1.1.1.  1,3,5,15
  16:      1.......1...1.11.  1,2,4,8,16
  17:     1...............1.  1,17
  18:    1........1..1..111.  1,2,3,6,9,18
  19:   1.................1.  1,19
  20:  1.........1....11.11.  1,2,4,5,10,20 (End)
		

Crossrefs

Programs

  • Mathematica
    Table[If[n == 0, 1, Total[10^Divisors[n]]], {n, 0, 20}] (* or *)
    Table[If[n == 0, 1, Sum[If[Mod[n, k] == 0, 10^k, 0], {k, n}]], {n, 0,
      20}] (* or *)
    Table[Boole[n == 0] + Total@ MapIndexed[Boole[Divisible[n, #1]]*10^First@ #2 &, Range@ n], {n, 0, 20}] (* or *)
    Table[If[n == 0, 1, Function[d, FromDigits @Reverse@ ReplacePart[#, Map[# + 1 -> 1 &, d]] &@ ConstantArray[0, n + 1]]@ Divisors@ n], {n, 0, 20}]
    (* Michael De Vlieger, May 24 2017 *)
  • PARI
    a(n) = if (n==0, 1, sum(k=1, n, if (! (n % k), 10^k))); \\ Michel Marcus, May 23 2017

Formula

a(n) = Sum_{k=0..n} if(mod(n, k)=0, 10^k, 0).
G.f.: Sum_{k>=1} 10^k*x^k/(1 - x^k). - Ilya Gutkovskiy, May 23 2017