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 A239696 Smallest number m such that m and reverse(m) each have n distinct prime factors. 1
 2, 6, 66, 858, 6006, 204204, 10444434, 208888680, 6172882716 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 10^11 < a(10) <= 438024420834. - Giovanni Resta, Mar 28 2014 LINKS EXAMPLE The first nontrivial example is a(6) = 204204. 204204 = 17*2^2*3*7*11*13 (6 distinct prime factors). 402402 = 2*3*7*67*11*13 (6 distinct prime factors). Since 204204 is the smallest number with this property, a(6) = 204204. PROG (Python) import sympy from sympy import factorint def Rev(x): ..rev = '' ..for i in str(x): ....rev = i + rev ..return int(rev) def RevFact(x): ..n = 2 ..while n < 10**8: ....if len(list(factorint(n).values())) == x: ......if len(list(factorint(Rev(n)).values())) == x: ........return n ......else: ........n += 1 ....else: ......n += 1 x = 1 while x < 50: ..print(RevFact(x)) ..x += 1 CROSSREFS Cf. A046399, A113548. Sequence in context: A055685 A262047 A280393 * A335645 A082619 A046399 Adjacent sequences:  A239693 A239694 A239695 * A239697 A239698 A239699 KEYWORD nonn,base,more AUTHOR Derek Orr, Mar 24 2014 EXTENSIONS a(8)-a(9) from Giovanni Resta, Mar 28 2014 STATUS approved

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Last modified January 28 23:12 EST 2022. Contains 350670 sequences. (Running on oeis4.)