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.

A101309 Matrix logarithm of A047999 (Pascal's triangle mod 2).

Original entry on oeis.org

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

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Author

Paul D. Hanna, Dec 23 2004

Keywords

Comments

Row sums equal A000120 (binary 1's-counting sequence). Antidiagonal sums form A101979.

Examples

			T(n,k)=1 when n XOR k is a power of 2:
T(3,2)=1 since 3 XOR 2 = 2^0, T(4,0)=1 since 4 XOR 0 = 2^2,
T(5,1)=1 since 5 XOR 1 = 2^2, T(6,4)=1 since 6 XOR 4 = 2^2.
Rows begin:
[0],
[1, 0],
[1,0, 0],
[0,1, 1,0],
[1,0,0,0, 0],
[0,1,0,0, 1,0],
[0,0,1,0, 1,0,0],
[0,0,0,1, 0,1,1,0],...
		

Crossrefs

Programs

  • PARI
    T(n,k)=if(n>k&bitxor(n,k)==2^valuation(bitxor(n,k),2),1,0)

Formula

T(n, k)=1 when n XOR k = 2^m for integer m>=0, T(n, k)=0 elsewhere.