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A230020
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Composite numbers n such that sigma(n) - reversal(n) = 1.
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2
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OFFSET
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1,1
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COMMENTS
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It is obvious that palindromic primes (palprimes) are all prime solutions of the equation sigma(x)-reversal(x) = 1. The next term is greater than 73*10^7.
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LINKS
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EXAMPLE
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sigma(9599) = sigma(29*331) = 30*332 = 9960 = reverse(9599)+1.
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MATHEMATICA
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Do[a=FromDigits[Reverse[IntegerDigits[n]]]; If[a>n && DivisorSigma[1, n] -a == 1, Print[n]], {n, 730000000}]
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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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