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 1-3 of 3 results.

A162438 a(1)=1, a(2)=2. Take terms a(n-1) and a(n-2), then convert to binary. Concatenate them, with either binary a(n-1) on the left and a(n-2) on the right, or with a(n-1) on the right and a(n-2) on the left such that the value of the resulting binary number is maximized. a(n) = the decimal equivalent of the resulting binary number.

Original entry on oeis.org

1, 2, 6, 26, 218, 7002, 1792858, 14687099738, 30801080592587610, 529158535306496354546309978, 19064945459410035469668296404984822042942298
Offset: 1

Views

Author

Leroy Quet, Jul 03 2009

Keywords

Comments

The difference between A162438(n) - A162437(n): 0, 0, 1, 5, 45, 1453, 372141, 3048582573, ..., . - Robert G. Wilson v, Jul 27 2009

Examples

			The binary representation of the first few terms: 1, 10, 110, 11010, 11011010.
		

Crossrefs

Programs

  • Mathematica
    a[1] = 1; a[2] = 2; a[n_] := Block[ {a1 = IntegerDigits[a[n - 1], 2], a2 = IntegerDigits[ a[n - 2], 2]}, Max[ FromDigits[ Join[a1, a2], 2], FromDigits[ Join[a2, a1], 2]]]; Array[a, 13] (* Robert G. Wilson v, Jul 27 2009 *)

Extensions

More terms from Robert G. Wilson v, Jul 27 2009

A162437 a(1)=1, a(2)=2. Take terms a(n-1) and a(n-2), then convert to binary. Concatenate them, with either binary a(n-1) on the left and a(n-2) on the right, or with a(n-1) on the right and a(n-2) on the left such that the value of the resulting binary number is minimized. a(n) = the decimal equivalent of the resulting binary number.

Original entry on oeis.org

1, 2, 5, 21, 173, 5549, 1420717, 11638517165, 24407739551034797, 419321772563920711635545517, 15107659029337673520218077770654501397966253
Offset: 1

Views

Author

Leroy Quet, Jul 03 2009

Keywords

Examples

			The binary representation of the first few terms: 1, 10, 101, 10101, 10101101
		

Crossrefs

Programs

  • Mathematica
    a[1] = 1; a[2] = 2; a[n_] := Block[{a1 = IntegerDigits[ a[n - 1], 2], a2 = IntegerDigits[ a[n - 2], 2]}, Min[ FromDigits[ Join[a1, a2], 2], FromDigits[ Join[a2, a1], 2]]]; Array[a, 13] (* Robert G. Wilson v, Jul 27 2009 *)

Extensions

More terms from Robert G. Wilson v, Jul 27 2009

A339713 a(n) = (a(n-2) concatenate a(n-1)) for n > 2, with a(1)=1, a(2)=10.

Original entry on oeis.org

1, 10, 110, 10110, 11010110, 1011011010110, 110101101011011010110, 1011011010110110101101011011010110, 1101011010110110101101011011010110110101101011011010110, 10110110101101101011010110110101101101011010110110101101011011010110110101101011011010110
Offset: 1

Views

Author

Wesley Ivan Hurt, Apr 24 2021

Keywords

Comments

Number of digits in a(n) = A000045(n+1). - Michael S. Branicky, Apr 24 2021
a(n) and a(n+1) contain Fibonacci(n) 1's and Fibonacci(n) 0's respectively.

Crossrefs

Cf. A000045, A111061 (in decimal), A061107, A131293.

Programs

  • Python
    def aupton(terms):
      alst = [1, 10]
      for n in range(3, terms+1): alst.append(int(str(alst[-2])+str(alst[-1])))
      return alst[:terms]
    print(aupton(10)) # Michael S. Branicky, Apr 24 2021
Showing 1-3 of 3 results.