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A061098
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Concatenation of all numbers less than or equal to n other than the phi(n) numbers relatively prime to n.
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1
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1, 2, 3, 24, 5, 2346, 7, 2468, 369, 2456810, 11, 2346891012, 13, 24678101214, 3569101215, 246810121416, 17, 234689101214151618, 19, 2456810121415161820, 36791214151821, 24681011121416182022, 23, 23468910121415161820212224, 510152025, 246810121314161820222426
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OFFSET
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1,2
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COMMENTS
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a(1) = 1 as the number itself is to be included. a(p) = p if p is a prime (by definition).
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LINKS
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EXAMPLE
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a(6) = 2346, as 2,3,4,6 are not coprime to 6 and 1 and 5 are coprime to 6.
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PROG
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(PARI) a(n)={if(n==1, 1, fromdigits(concat([digits(k) | k<-[1..n], gcd(k, n)>1])))} \\ Andrew Howroyd, Nov 09 2019
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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Offset corrected and terms a(14) and beyond from Andrew Howroyd, Nov 09 2019
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STATUS
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approved
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