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.

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A272776 Numbers k such that phi(Fibonacci(k)) is a square.

Original entry on oeis.org

1, 2, 3, 5, 6, 9, 22, 33
Offset: 1

Views

Author

Altug Alkan, May 06 2016

Keywords

Comments

Corresponding distinct Fibonacci numbers for listed terms are 1, 2, 5, 8, 34, 17711, 3524578.
a(9) > 1000 (range of the b-file in A065449), if it exists. - R. J. Mathar, May 08 2016

Crossrefs

Cf. A000010, A000045, A000290, A065449.

Programs

  • PARI
    lista(nn) = for(n=1, nn, if(issquare(eulerphi(fibonacci(n))), print1(n, ", ")));

A278350 Cototient of Fibonacci(n).

Original entry on oeis.org

0, 0, 1, 1, 1, 4, 1, 9, 18, 15, 1, 96, 1, 41, 370, 435, 1, 1432, 149, 3565, 5906, 287, 1, 33696, 15025, 753, 106562, 129651, 1, 544040, 2973, 960597, 1782178, 5167, 2413385, 10534320, 501497, 1397033, 31758946, 60862155, 62157, 149373496, 1
Offset: 1

Views

Author

Altug Alkan, Nov 19 2016

Keywords

Comments

a(n) = 1 if Fibonacci(n) is prime.

Crossrefs

Cf. A000045, A051953, A065449.

Programs

  • Mathematica
    Table[Fibonacci[n] - EulerPhi[Fibonacci[n]], {n, 40}] (* Alonso del Arte, Nov 21 2016 *)
  • PARI
    a(n) = fibonacci(n) - eulerphi(fibonacci(n));

Formula

a(n) = A051953(A000045(n)).
a(n) = A000045(n) - A065449(n) for n > 0.
Previous Showing 11-12 of 12 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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