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.

A222296 Irregular triangle read by rows: row n lists the Fibonacci numbers with exactly n 1's in their binary representation.

Original entry on oeis.org

0, 1, 1, 2, 8, 3, 5, 34, 144, 13, 21
Offset: 0

Views

Author

T. D. Noe, Feb 22 2013

Keywords

Comments

Besides those listed in Example section, there are no additional terms with small number of 1's in the first 10^12 Fibonacci numbers. In particular, if A000120(Fibonacci(n)) < 100, then n <= 319 or n > 10^12. - Charles R Greathouse IV, Mar 06 2014
For the theorem about S-units that Noam Elkies quotes (in the MathOverflow link), see Chapter 1 of Storey-Tijdemann, 1986. - N. J. A. Sloane, Jan 28 2017

Examples

			The irregular table begins
{0},
{1, 1, 2, 8},
{3, 5, 34, 144},
{13, 21, ...}.
It is conjectured that the previous (n=3) row is complete, and that the subsequent rows are:
{89, 610, 2584},
{55, 233, 4181},
{377, 10946, 46368, 75025},
{1597},
{987, 6765, 17711, 832040},
{121393, 2178309},
{39088169},
{28657, 196418, 317811, 1346269, 9227465},
{514229, 5702887, 14930352, 63245986, 4807526976},
{3524578, 2971215073}
...
		

References

  • T. N. Shorey and R. Tijdeman, Exponential Diophantine Equations, Cambridge Tracts in Mathematics, 1986.

Crossrefs

Cf. A004685 (Fibonacci numbers in binary), A221158 (weight 2), A222295, A222601, A222602, A222757, A222758.

Programs

  • Mathematica
    f = Fibonacci[Range[0,100]]; Table[Select[f, Total[IntegerDigits[#, 2]] == n &], {n, 0, 20}]
  • PARI
    row(n)=my(k=-1,t); while(1,t=fibonacci(k++); if(hammingweight(t)==n, print1(t", "))) \\ Charles R Greathouse IV, Mar 04 2014

Extensions

a(9)-a(10) from Noam D. Elkies, via Charles R Greathouse IV, Mar 04 2014
Truncated to established terms by Max Alekseyev, May 13 2014
Edited by Max Alekseyev, Sep 08 2016

A222295 Conjectured number of Fibonacci numbers with exactly n bits set in their binary representation.

Original entry on oeis.org

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

Views

Author

T. D. Noe, Feb 22 2013

Keywords

Examples

			We set a(1) = 4 because Fib(1) = 1, Fib(2) = 1, Fib(3) = 2, and Fib(6) = 8.
		

Crossrefs

Cf. A004685 (Fibonacci numbers in binary), A221158 (two bits set), A222296.
Cf. A011373 (number of bits set in each Fibonacci number).

Programs

  • Mathematica
    f = Fibonacci[Range[0,500]]; Table[Length[Select[f, Total[IntegerDigits[#, 2]] == n &]], {n, 0, 87}]

A214853 Fibonacci numbers with only one 0 in the binary representation.

Original entry on oeis.org

0, 2, 5, 13, 55
Offset: 1

Views

Author

Alex Ratushnyak, Mar 08 2013

Keywords

Comments

Conjecture: the sequence is finite.
No more terms below 2*10^301. - Matthew House, Sep 06 2015
No more terms below 10^162809483. (This number could easily be raised. Of the Fibonacci numbers less than 2^32 -- i.e., F(0) through F(47) -- F(10)=55 is the largest that has only one 0 in its binary representation, and of those not less than 2^32, the smallest one whose 32 least significant bits include fewer than 2 zero bits is Fibonacci(779038816), which exceeds 10^162809483.) - Jon E. Schoenfield, Sep 07 2015

Examples

			55 is 110111 in binary, thus 55 is in the sequence.
		

Crossrefs

Intersection of A030130 and A000045.

Programs

  • Mathematica
    Select[Fibonacci@ Range[0, 120], Last@ DigitCount[#, 2] == 1 &] (* Michael De Vlieger, Sep 07 2015 *)
  • Python
    def count0(x):
        c = 0
        while x:
            c+= 1 - (x&1)
            if c>1:
                return 2
            x>>=1
        return c
    prpr, prev = 0,1
    TOP = 1<<12
    print(0, end=',')
    for i in range(1,TOP):
        if count0(prpr)==1:
            print(prpr, end=',')
        if (i&4095)==0:
            print('.', end=',')
        prpr, prev = prev, prpr+prev
Showing 1-3 of 3 results.