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 A075815 Palindromic odd composite numbers with an odd number of prime factors (counted with multiplicity). 1
 99, 171, 333, 343, 363, 555, 575, 595, 747, 777, 909, 969, 1001, 1221, 1331, 1551, 1771, 3333, 3553, 5335, 5445, 5555, 5665, 5775, 5885, 5995, 7337, 7557, 7667, 7777, 7887, 9009, 9339, 9559, 9669, 9779, 9889, 11211, 11511, 11711, 11811, 12121 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 EXAMPLE 5445=3^2*5*11^2 and 5555=5*11*101 are palindromic, odd, composite and have an odd number of prime factors. MAPLE test := proc(n) local d; d := convert(n, base, 10); return ListTools[Reverse](d)=d and type(numtheory[bigomega](n), odd) and not isprime(n); 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[9, 13000, 2], PalindromeQ[#]&&CompositeQ[#]&&OddQ[ PrimeOmega[ #]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 28 2021 *) CROSSREFS Cf. A046389. Sequence in context: A185498 A126230 A055164 * A075814 A320707 A235228 Adjacent sequences: A075812 A075813 A075814 * A075816 A075817 A075818 KEYWORD nonn,base AUTHOR Jani Melik, Oct 13 2002 EXTENSIONS Edited by Dean Hickerson, Oct 21 2002 STATUS approved

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Last modified September 8 05:26 EDT 2024. Contains 375751 sequences. (Running on oeis4.)