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.

A057659 Prime numbers whose square is composed of just two different decimal digits.

This page as a plain text file.
%I A057659 #27 Feb 11 2025 02:28:02
%S A057659 5,7,11,109,173,81619
%N A057659 Prime numbers whose square is composed of just two different decimal digits.
%C A057659 Conjectured to be a finite sequence.
%C A057659 No further terms up to prime(1000000)=15485863. - _Harvey P. Dale_, Mar 20 2011
%D A057659 Related to the Unsolved problem F24, p. 262, of the UPiNT by _R. K. Guy_
%e A057659 81619^2 = 6661661161.
%p A057659 filter:= p -> nops(convert(convert(p^2,base,10),set))= 2:
%p A057659 select(filter, [seq(ithprime(i),i=1..10^5)]); # _Robert Israel_, Feb 11 2025
%t A057659 Select[Prime[Range[10000]],Count[DigitCount[#^2],0] ==8&] (* _Harvey P. Dale_, Mar 20 2011 *)
%o A057659 (PARI) select(x->#Set(digits(x^2))==2, primes(10000)) \\ _Michel Marcus_, Feb 11 2025
%Y A057659 Subsequence of A016069.
%Y A057659 Cf. A235154.
%K A057659 nonn,base,more
%O A057659 1,1
%A A057659 _Carlos Rivera_, Oct 15 2000