A075814 Palindromic odd numbers with exactly 3 prime factors (counted with multiplicity).

99, 171, 333, 343, 363, 555, 575, 595, 747, 777, 909, 969, 1001, 1221, 1331, 1551, 1771, 3333, 3553, 5335, 5555, 5665, 5885, 5995, 7337, 7557, 7667, 7777, 7887, 9339, 9559, 9669, 9779, 9889, 11211, 11511, 11711, 11811, 12121, 12221, 12621, 12921

Offset: 1

Author

Jani Melik, Oct 13 2002

Keywords

• nonn
• base

Examples

			99=3^2*11, 171=3^2*19 and 333=3^2*37 are palindromic, odd and have exactly 3 prime factors.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A046316.

Programs

Maple

test := proc(n) local d; d := convert(n,base,10); return ListTools[Reverse](d)=d and numtheory[bigomega](n)=3; end; a := []; for n from 1 to 13000 by 2 do if test(n) then a := [op(a),n]; end; od; a;

Mathematica

Select[Range[1,13001,2],PalindromeQ[#]&&PrimeOmega[#]==3&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 05 2017 *)075814:"

Extensions

Edited by Dean Hickerson, Oct 21 2002