A046404 Odd numbers with exactly 2 distinct palindromic prime factors.

15, 21, 33, 35, 55, 77, 303, 393, 453, 505, 543, 573, 655, 707, 755, 905, 917, 939, 955, 1057, 1059, 1111, 1119, 1149, 1267, 1337, 1441, 1565, 1661, 1765, 1865, 1915, 1991, 2101, 2181, 2191, 2271, 2361, 2391, 2471, 2611, 2681, 2757, 2787, 3443, 3635, 3785

Offset: 1

Author

Patrick De Geest, Jun 15 1998

Keywords

• nonn
• base

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..501

Crossrefs

Intersection of A033620 and A046388.

Cf. A046372.

Programs

Mathematica

dpf2Q[n_]:=Module[{pfs=Transpose[FactorInteger[n]][[1]],a,b},a=First[pfs];b=Last[pfs];PrimeNu[n]==PrimeOmega[n]==2 && a==FromDigits[Reverse[ IntegerDigits[ a]]] && b==FromDigits[Reverse[ IntegerDigits[b]]]]; Select[ Range[1,3801,2],dpf2Q] (* Harvey P. Dale, Jul 14 2013 *)

Extensions

Offset changed by Andrew Howroyd, Aug 14 2024