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.

A253576 Primes p such that digits of p do not appear in p^7.

Original entry on oeis.org

3, 7, 43, 7757, 31333
Offset: 1

Views

Author

Vincenzo Librandi, Jan 04 2015

Keywords

Comments

a(6) > 10^9. - Chai Wah Wu, Jan 05 2015

Examples

			3 and 3^7 = 2187 have no digits in common, hence 3 is in the sequence.
		

Crossrefs

Prime numbers in A281678.
Cf. similar sequences listed in A253574.

Programs

  • Mathematica
    Select[Prime[Range[1000000]], Intersection[IntegerDigits[#], IntegerDigits[#^7]]=={} &]
  • Python
    from sympy import isprime
    A253576_list = [n for n in range(1,10**6) if set(str(n)) & set(str(n**7)) == set() and isprime(n)]
    # Chai Wah Wu, Jan 05 2015

A281148 Numbers k such that k and k^6 have no digits in common.

Original entry on oeis.org

2, 3, 8, 9, 13, 14, 22, 33, 44, 52, 72, 77, 87, 92, 222, 322, 622, 7737, 7878, 30302, 44449, 72777, 844844, 44744744
Offset: 1

Views

Author

Robert Israel and Altug Alkan, Jan 27 2017

Keywords

Comments

0, 1, 5, 6 cannot be the last digit of any term. [0 added to list by Jon E. Schoenfield, Jan 29 2017]
The only terms with no repeated digits are 2, 3, 8, 9, 13, 14, 52, 72, 87, 92.
If it exists, a(25) > 10^17. - David Radcliffe, May 26 2025

Examples

			92 is a term because 92^6 = 606355001344 has no digit 2 or 9.
		

Crossrefs

Programs

  • Mathematica
    fQ[n_] := Intersection[IntegerDigits[n], IntegerDigits[n^6]] == {}; Select[ Range@45000000, Mod[#, 5] > 1 && fQ@# &] (* Robert G. Wilson v, Jan 29 2017 *)
  • PARI
    isok(n) = #setintersect(Set(digits(n)), Set(digits(n^6))) == 0;
Showing 1-2 of 2 results.