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 A046448 Squarefree nonprimes with property that the concatenation of the prime factors is a palindrome. 3
 1, 39, 69, 119, 129, 159, 219, 249, 259, 329, 339, 403, 429, 469, 669, 679, 795, 1207, 1309, 1329, 1533, 1547, 1589, 1703, 2319, 2321, 2359, 2649, 2701, 3039, 3421, 3503, 3629, 3633, 3639, 3729, 3899, 4303, 4607, 4839, 5289, 5295, 5565, 5603, 5739, 6209 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..46. EXAMPLE E.g., 429 = 3 * 11 * 13 -> 31113 is palindromic. MATHEMATICA Select[Range[6210], ! PrimeQ[#] && SquareFreeQ[#] && Reverse[x = Flatten[IntegerDigits[First /@ FactorInteger[#]]]] == x &] (* Jayanta Basu, Jun 24 2013 *) Select[Range[6500], !PrimeQ[#]&&SquareFreeQ[#]&&PalindromeQ[ FromDigits[ Flatten[ IntegerDigits/@ FactorInteger[#][[All, 1]]]]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 25 2020 *) CROSSREFS Cf. A046447, A046449, A046450, A002113. Sequence in context: A090876 A165461 A020166 * A249701 A039467 A250657 Adjacent sequences: A046445 A046446 A046447 * A046449 A046450 A046451 KEYWORD nonn,base AUTHOR Patrick De Geest, Jul 15 1998 EXTENSIONS Definition clarified by N. J. A. Sloane, Oct 25 2020 STATUS approved

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Last modified October 4 09:13 EDT 2023. Contains 365873 sequences. (Running on oeis4.)