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A241473
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a(n) is the smallest k such that phi(k) = reverse(k-n), or 0 if no such k exists.
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0
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2, 4, 9, 6, 26, 10, 15, 12, 6543, 52, 74, 18, 76, 56, 36, 24, 289, 27888, 43, 104, 42, 30, 63449, 46, 49, 6398, 115, 51, 2561, 72, 27262, 445685, 118, 48517846, 2246, 78, 268
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OFFSET
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1,1
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COMMENTS
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phi(n) = A000010(n) is the Euler totient function.
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LINKS
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EXAMPLE
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a(23) = 63449 because phi(63449) = 62436 = reverse(63426) = reverse(63449-23).
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MATHEMATICA
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Table[k = n+1; While[EulerPhi[k] != FromDigits[ Reverse[ IntegerDigits[k-n] ]], k++]; k, {n, 25}]
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PROG
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(PARI) a(n) = {my(k = n+1); while (eulerphi(k) != fromdigits(Vecrev(digits(k-n))), k++); k; } \\ Michel Marcus, Sep 18 2017
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CROSSREFS
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KEYWORD
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nonn,base,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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