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A275451
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Number of occurrences of the string n in primorial(n).
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1
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0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 1, 1, 0, 2, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 3, 0, 0, 3, 2, 2, 1, 1, 1, 1, 2, 0, 5, 4, 4, 2, 4, 4, 0, 0, 4, 2, 4, 3, 1, 0, 1, 0, 1, 2
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OFFSET
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1,36
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LINKS
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FORMULA
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EXAMPLE
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Primorial(3) equals 30, which contains 3 once, therefore a(3) = 1.
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MATHEMATICA
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primorial[n_]:=Product[Prime[i], {i, 1, n}];
Table[Length[StringPosition[ToString[primorial[n]], ToString[n]]], {n, 1, 100}]
SequenceCount[IntegerDigits[#[[1]]], IntegerDigits[#[[2]]]]&/@With[ {nn=90}, Thread[ {FoldList[ Times, Prime[Range[nn]]], Range[nn]}]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 16 2017 *)
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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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STATUS
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approved
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