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.

A191904 Square array read by antidiagonals up: T(n,k) = 1-k if k divides n, else 1.

Original entry on oeis.org

0, 0, 1, 0, -1, 1, 0, 1, 1, 1, 0, -1, -2, 1, 1, 0, 1, 1, 1, 1, 1, 0, -1, 1, -3, 1, 1, 1, 0, 1, -2, 1, 1, 1, 1, 1, 0, -1, 1, 1, -4, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, -1, -2, -3, 1, -5, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, -1, 1, 1, 1, 1, -6, 1, 1, 1, 1, 1, 1, 0, 1, -2, 1, -4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, -1, 1, -3, 1, 1, 1, -7, 1, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Mats Granvik, Jun 19 2011

Keywords

Comments

Transposed variant of A177121. Array variant of A176079.

Examples

			Table begins:
0..1..1..1..1..1..1..1..1...
0.-1..1..1..1..1..1..1..1...
0..1.-2..1..1..1..1..1..1...
0.-1..1.-3..1..1..1..1..1...
0..1..1..1.-4..1..1..1..1...
0.-1.-2..1..1.-5..1..1..1...
0..1..1..1..1..1.-6..1..1...
0.-1..1.-3..1..1..1.-7..1...
0..1.-2..1..1..1..1..1.-8...
		

Crossrefs

Programs

  • Mathematica
    nn = 30; t[n_, k_] := t[n, k] = If[Mod[n, k] == 0, -(k - 1), 1]; MatrixForm[Table[Table[t[n, k], {k, 1, nn}], {n, 1, nn}]]

Formula

Conjecture: Sum_{n>=1} T(n,k)/n = log(k).
From Mats Granvik, Apr 24 2022: (Start)
Sum recurrence:
T(n, 1) = [n >= 1]*0;
T(n, k) = [n < k]*1;
T(n, k) = [n >= k](Sum_{i=1..k-1} T(n - i, k - 1) - Sum_{i=1..k-1} T(n - i, k)).
Product recurrence:
T(n, 1) = [n >= 1]*0;
T(n, k) = [n < k]*1;
T(n, k) = [n >= k](Product_{i=1..k-1} T(n - i, k - 1) - Product_{i=1..k-1} T(n - i, k)).
(End)

A127511 a(n) = mu(n) * 2^(n-1).

Original entry on oeis.org

1, -2, -4, 0, -16, 32, -64, 0, 0, 512, -1024, 0, -4096, 8192, 16384, 0, -65536, 0, -262144, 0, 1048576, 2097152, -4194304, 0, 0, 33554432, 0, 0, -268435456, -536870912, -1073741824, 0, 4294967296, 8589934592, 17179869184, 0, -68719476736, 137438953472, 274877906944, 0, -1099511627776
Offset: 1

Views

Author

Gary W. Adamson, Jan 17 2007

Keywords

Comments

Row sums of A127512.
Appears to be the determinant of A156734 where the element in the lower right corner has been swapped with the element in the upper right corner. - Mats Granvik, Feb 14 2009

Examples

			a(5) = (-1)*16 = -16 since mu(5) = -1 and 2^4 = 16.
		

Crossrefs

Programs

  • Maple
    A127511 := proc(n) 2^(n-1)*numtheory[mobius](n) ; end: for n from 1 to 50 do printf("%d, ",A127511(n)) ; od ; # R. J. Mathar, May 19 2007
  • Mathematica
    Array[MoebiusMu[#]*2^(#-1)&,41] (* James C. McMahon, Jan 02 2025 *)

Formula

a(n)=A008683(n)*A000079(n-1). - R. J. Mathar, May 19 2007

Extensions

More terms from R. J. Mathar, May 19 2007
Showing 1-2 of 2 results.