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.

A211968 Triangle of binary numbers with some initial repeats.

Original entry on oeis.org

11, 110, 111, 1010, 1100, 1101, 1110, 1111, 10100, 10101, 11000, 11001, 11010, 11011, 11100, 11101, 11110, 11111, 100100, 101000, 101001, 101010, 101011, 101101, 110000, 110001, 110010, 110011, 110100, 110101, 110110, 110111, 111000, 111001, 111010, 111011
Offset: 2

Views

Author

Omar E. Pol, Dec 03 2012

Keywords

Comments

Triangle read by rows in which row n lists the binary numbers with n digits and with some initial repeats, n >= 2.
Also triangle read by rows in which row n lists the binary words of length n with some initial repeats and with initial digit 1, n >= 2.

Examples

			Triangle begins, starting at row 2:
  11;
  110, 111;
  1010, 1100, 1101, 1110, 1111;
  10100, 10101, 11000, 11001, 11010, 11011, 11100, 11101, 11110, 11111;
		

Crossrefs

Complement in base 2 of A211027.
Rows lengths give: A093370.

Programs

  • Maple
    s:= proc(n) s(n):= `if`(n=1, [[1]], map(x->
          [[x[], 0], [x[], 1]][], s(n-1))) end:
    T:= proc(n) map(x-> parse(cat(x[])), select(proc(l) local i;
          for i to iquo(nops(l), 2) do if l[1..i]=l[i+1..2*i]
          then return true fi od; false end, s(n)))[] end:
    seq(T(n), n=2..7);  # Alois P. Heinz, Dec 04 2012
  • Mathematica
    T[n_] := FromDigits /@ Select[Range[2^(n-1), 2^n-1] // IntegerDigits[#, 2]&, FindTransientRepeat[Reverse[#], 2][[2]] != {}&];
    Table[T[n], {n, 2, 7}] // Flatten (* Jean-François Alcover, Feb 12 2025 *)

A211969 Triangle of decimal equivalents of binary numbers with some initial repeats, A211968.

Original entry on oeis.org

3, 6, 7, 10, 12, 13, 14, 15, 20, 21, 24, 25, 26, 27, 28, 29, 30, 31, 36, 40, 41, 42, 43, 45, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 72, 73, 80, 81, 82, 83, 84, 85, 86, 87, 90, 91, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106
Offset: 2

Views

Author

Omar E. Pol, Dec 03 2012

Keywords

Examples

			Irregular triangle begins, starting at row 2:
3;
6, 7;
10, 12, 13, 14, 15;
20, 21, 24, 25, 26, 27, 28, 29, 30, 31;
36, 40, 41, 42, 43, 45, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63;
		

Crossrefs

Complement of A211967.
Row lengths give: A093370.
Column 1 gives: A005418(n+1).
Right border gives: A000225(n).

Programs

  • Maple
    s:= proc(n) s(n):= `if`(n=1, [[1]], map(x->
          [[x[], 0], [x[], 1]][], s(n-1))) end:
    T:= proc(n) map (x-> add(x[i]*2^(nops(x)-i), i=1..nops(x)), select
          (proc(l) local i; for i to iquo(nops(l), 2) do if l[1..i]=
          l[i+1..2*i] then return true fi od; false end, s(n)))[] end:
    seq (T(n), n=2..7);  # Alois P. Heinz, Dec 04 2012
Showing 1-2 of 2 results.