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A342347
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a(1) = 7, a(n) = smallest palindromic nontrivial multiple of a(n-1) containing all decimal digits of a(n-1).
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0
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OFFSET
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1,1
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COMMENTS
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a(n) <= (10^A055642(a(n-1))+1)*a(n-1).
If a(n-1) > 10 and the last digit of a(n-1) <= 4, then a(n) <= (10^(A055642(a(n-1))-1)+1)*a(n-1).
For n=6..8, a(n) = 196930692 * A002275(2^(n-3)), and it follows that a(9) <= 196930692 * A002275(64). Conjecture: for all n >= 6, a(n) = 196930692 * A002275(2^(n-3)). Note that 196930692 is a term of A370052 and A370053. - Max Alekseyev, Feb 15 2024
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LINKS
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EXAMPLE
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a(3) = 1771 is a palindromic multiple of a(2) = 77 and contains two '7', all the digits of a(2).
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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