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 A087305 Smallest n-digit non-palindromic number such that it and its digit reversal have the same prime signature. 0
 13, 107, 1002, 10002, 100006, 1000007, 10000013, 100000005, 1000000007, 10000000006, 100000000007, 1000000000006, 10000000000003, 100000000000002, 1000000000000003, 10000000000000002, 100000000000000005, 1000000000000000005, 10000000000000000021, 100000000000000000031 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Table of n, a(n) for n=2..21. EXAMPLE a(6) = 100006 = 2*13*1613 and 600001 = 19*23*1373 both have prime signature p*q*r, p,q,r are primes. PROG (PARI) rev(n) = fromdigits(Vecrev(digits(n))); psig(n) = vecsort(factor(n)[, 2]~); a(n) = {my(k = 10^n+1); while(k == rev(k) || psig(k) != psig(rev(k)), k++); k; } \\ Amiram Eldar, May 19 2024 CROSSREFS Cf. A085869, A068893. Sequence in context: A142364 A164301 A322499 * A168117 A244176 A038384 Adjacent sequences: A087302 A087303 A087304 * A087306 A087307 A087308 KEYWORD base,nonn,changed AUTHOR Amarnath Murthy, Sep 02 2003 EXTENSIONS More terms from David Wasserman, Apr 19 2005 More terms from Amiram Eldar, May 19 2024 STATUS approved

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Last modified May 27 20:38 EDT 2024. Contains 372882 sequences. (Running on oeis4.)