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

1,1

Links

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

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 *)

Crossrefs

Intersection of A033620 and A046388.

Cf. A046372.

Sequence in context: A321644 A225709 A020162 * A198680 A300117 A214044

Adjacent sequences: A046401 A046402 A046403 * A046405 A046406 A046407

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

Extensions

Offset changed by Andrew Howroyd, Aug 14 2024

Status

approved