login
The largest palindromic prime dividing n, or 0 if such a prime does not exist.
2

%I #8 Apr 18 2019 02:54:18

%S 2,3,2,5,3,7,2,3,5,11,3,0,7,5,2,0,3,0,5,7,11,0,3,5,2,3,7,0,5,0,2,11,2,

%T 7,3,0,2,3,5,0,7,0,11,5,2,0,3,7,5,3,2,0,3,11,7,3,2,0,5,0,2,7,2,5,11,0,

%U 2,3,7,0,3,0,2,5,2,11,3,0,5,3,2,0,7,5,2,3,11,0,5,7,2,3,2,5,3,0,7,11,5,101,3,0

%N The largest palindromic prime dividing n, or 0 if such a prime does not exist.

%p read("transforms") : isA002113 := proc(n) simplify(digrev(n) = n ); end proc:

%p isA002385 := proc(n) isprime(n) and isA002113(n) ; end proc:

%p A180506 := proc(n) fs := sort(convert(numtheory[factorset](n),list)) ; for i from 1 to nops(fs) do if isA002385(op(-i,fs)) then return op(-i,fs) ; end if; end do: return 0 ; end proc:

%p seq(A180506(n),n=2..104) ; # _R. J. Mathar_, Sep 19 2010

%Y Cf. A002385.

%K base,nonn

%O 2,1

%A _Giovanni Teofilatto_, Sep 09 2010

%E Offset and some values corrected by _R. J. Mathar_, Sep 19 2010