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.

A109433 Triangle read by rows: T(n,m) = number of binary numbers n+1 digits long which have m 1's as a substring.

Original entry on oeis.org

1, 2, 1, 4, 2, 1, 8, 5, 2, 1, 16, 11, 5, 2, 1, 32, 24, 12, 5, 2, 1, 64, 51, 27, 12, 5, 2, 1, 128, 107, 60, 28, 12, 5, 2, 1, 256, 222, 131, 63, 28, 12, 5, 2, 1, 512, 457, 282, 140, 64, 28, 12, 5, 2, 1, 1024, 935, 601, 307, 143, 64, 28, 12, 5, 2, 1, 2048, 1904, 1270, 666, 316, 144
Offset: 0

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Author

Robert G. Wilson v, Jun 27 2005

Keywords

Examples

			T(4,2)=11 because of the sixteen binary digits which are 5 long, {10000, 10001, 10010, 10011, 10100, 10101, 10110, 10111, 11000, 11001, 11010, 11011, 11100, 11101, 11110, 11111}, 11 have "11" as a substring.
Triangle begins:
n\m
0 1 0 0 0 0 0 0 0 0 0
1 2 1 0 0 0 0 0 0 0 0
2 4 2 1 0 0 0 0 0 0 0
3 8 5 2 1 0 0 0 0 0 0
4 16 11 5 2 1 0 0 0 0 0
5 32 24 12 5 2 1 0 0 0 0
		

Crossrefs

First column = A000079 = Powers of 2, the second column = A027934 = number of compositions of n with at least one even part and the last column = A045623 = number of 1's in all compositions of n+1.

Programs

  • Mathematica
    T[n_, m_] := Length[ Select[ StringPosition[ #, ToString[(10^m - 1)/9]] & /@ Table[ ToString[ FromDigits[ IntegerDigits[i, 2]]], {i, 2^n, 2^(n + 1) - 1}], # != {} &]]; Flatten[ Table[ T[n, m], {n, 0, 11}, {m, n + 1}]]