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.

A155033 Matrix inverse of A155031.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 3, 2, 1, 1, 0, 4, 3, 2, 1, 1, 0, 10, 7, 4, 2, 1, 1, 0, 18, 13, 7, 4, 2, 1, 1, 0, 37, 26, 15, 8, 4, 2, 1, 1, 0, 71, 51, 29, 15, 8, 4, 2, 1, 1, 0, 146, 104, 59, 31, 16, 8, 4, 2, 1, 1, 0, 285, 203, 115, 61, 31, 16, 8, 4, 2, 1, 1, 0, 577, 411, 233, 123, 63, 32, 16, 8, 4, 2, 1, 1
Offset: 1

Views

Author

Mats Granvik, Jan 19 2009

Keywords

Examples

			Table begins and row sums are:
  1                            =  1;
  0,  1                        =  1;
  0,  1,  1                    =  2;
  0,  1,  1,  1                =  3;
  0,  3,  2,  1, 1             =  7;
  0,  4,  3,  2, 1, 1          = 11;
  0, 10,  7,  4, 2, 1, 1       = 25;
  0, 18, 13,  7, 4, 2, 1, 1    = 46;
  0, 37, 26, 15, 8, 4, 2, 1, 1 = 94;
		

Crossrefs

Cf. A101173.

Programs

  • Mathematica
    A155031[n_, k_]:= If[k>n, 0, If[k==n, 1, If[k==1 || Mod[n, k]==0, 0, -1]]];
    A155033:= Inverse[Table[A155031[n, k], {n,30}, {k,30}]];
    Table[A155033[[n, k]], {n,15}, {k,n}]//Flatten (* G. C. Greubel, Mar 15 2021 *)

Formula

Sum_{k=1..n} T(n,k) = A101173(n). - G. C. Greubel, Mar 15 2021

A155029 Complement to A051731 with the identity matrix A023531 included.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Mats Granvik, Jan 19 2009

Keywords

Examples

			Table begins:
  1;
  0, 1;
  0, 1, 1;
  0, 0, 1, 1;
  0, 1, 1, 1, 1;
  0, 0, 0, 1, 1, 1;
  0, 1, 1, 1, 1, 1, 1;
  0, 0, 1, 0, 1, 1, 1, 1;
  0, 1, 0, 1, 1, 1, 1, 1, 1;
		

Crossrefs

Programs

  • Magma
    [k eq n select 1 else (k eq 0 or n mod k eq 0) select 0 else 1: k in [1..n], n in [1..20]]; // G. C. Greubel, Mar 07 2021
  • Mathematica
    Table[If[k==n, 1, If[k==0, 0, If[Mod[n, k]==0, 0, 1]]], {n, 20}, {k, n}]//Flatten (* G. C. Greubel, Mar 07 2021 *)
  • Sage
    flatten([[1 if k==n else 0 if (k==0 or n%k==0) else 1 for k in [1..n]] for n in [1..20]]) # G. C. Greubel, Mar 07 2021
    

Formula

T(n, k) = 0 if n==0 (mod k) otherwise 1 with T(n, n) = 1 and T(n, 1) = 0. - G. C. Greubel, Mar 07 2021
Showing 1-2 of 2 results.