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A081227
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a(n) is the number of digits in common between n and the n-th prime in base 10.
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2
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0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 2
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OFFSET
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1,73
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COMMENTS
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Duplicate digits are ignored for comparison purposes; e.g. 1002 and 3050 only have one digit in common, 0.
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LINKS
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EXAMPLE
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a(7)=1 since the 7th prime is 17.
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MAPLE
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digcomp := proc(A, B) local a, b, crit, f; description "returns the digits that 'A' and 'B' have in common; if a third argument is given and it is 'sum' then the sum of the common digits is returned, else if it is 'num' then the number of common digits is returned."; if nargs>2 then crit := args[3] else crit := NULL fi; a := convert(`if`(A=0, [0], (convert(A, base, 10))), set); b := convert(`if`(B=0, [0], (convert(B, base, 10))), set); f := a intersect b; if crit=sum then return `if`(nops(f)>0, `+`(op(f)), -1) elif crit=num then return nops(f) else return f; fi; end proc;
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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Francois Jooste (pin(AT)myway.com), Mar 11 2003
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STATUS
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approved
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