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A281066
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Concatenation R(n)R(n-1)R(n-2)...R(2)R(1) read mod n, where R(x) is the digit-reversal of x (with leading zeros not omitted).
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2
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0, 1, 0, 1, 1, 3, 3, 1, 0, 1, 4, 9, 5, 7, 6, 1, 6, 9, 17, 1, 15, 15, 19, 9, 21, 1, 18, 13, 28, 21, 26, 17, 15, 3, 16, 9, 30, 3, 15, 1, 1, 33, 10, 37, 36, 43, 22, 33, 19, 21, 48, 45, 2, 45, 26, 49, 27, 33, 33, 21, 48, 25, 36, 49, 36, 15, 22, 5, 27, 11, 42, 9, 2, 73, 21, 17, 59, 57, 5, 1
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OFFSET
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1,6
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LINKS
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FORMULA
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EXAMPLE
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a(13) = 31211101987654321 (mod 13) = 5.
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MATHEMATICA
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f[n_] := Mod[ FromDigits@ Fold[ Join[ Reverse@ IntegerDigits@#2, #1] &, {}, Range@ n], n]; Array[f, 80]
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PROG
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(Python)
....s=""
....for i in range(n, 0, -1):
........s+=str(i)[::-1]
(PARI) a(n) = my(s = ""); forstep (k=n, 1, -1, sk = digits(k); forstep (j=#sk, 1, -1, s = concat(s, sk[j]))); eval(s) % n; \\ Michel Marcus, Jan 28 2017
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CROSSREFS
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KEYWORD
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nonn,easy,base
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AUTHOR
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STATUS
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approved
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