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Search: id:A115208
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| A115208 |
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a(1)=0. a(n) = number of earlier terms of the sequence which when added to n produce a composite number. |
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+0
4
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| 0, 0, 0, 3, 1, 4, 2, 6, 6, 7, 4, 9, 5, 10, 11, 12, 9, 14, 11, 14, 18, 17, 14, 20, 18, 20, 17, 23, 18, 22, 22, 26, 23, 29, 26, 26, 26, 30, 28, 36, 23, 34, 30, 34, 31, 43, 30, 40, 33, 37, 43, 45, 31, 46, 42, 44, 40, 48, 42, 48, 39, 52, 47, 53
(list; graph; listen)
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OFFSET
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1,4
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EXAMPLE
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Adding 7 to the first 6 terms of the sequence gives [7,7,7,10,8,11]. Of these terms, two are composite, so a(7) = 2.
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MATHEMATICA
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a = {0, 0}; For[n = 3, n < 90, n++, in = 0; For[j = 1, j < Length[a] + 1, j++, If[ ! PrimeQ[n + a[[j]]], in++ ]]; AppendTo[a, in]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 03 2007
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CROSSREFS
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Cf. A115207, A115209, A115210.
Sequence in context: A066728 A066899 A139432 this_sequence A067060 A115659 A068028
Adjacent sequences: A115205 A115206 A115207 this_sequence A115209 A115210 A115211
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Jan 16 2006
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 03 2007
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