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A175144
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a(n) = d(p(n)-1) + d(p(n)+1), where p(n) is the n-th prime, and where d(m) is the number of divisors of m.
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6
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3, 5, 7, 8, 10, 10, 11, 12, 12, 14, 14, 13, 16, 14, 14, 14, 16, 16, 14, 20, 16, 18, 16, 20, 18, 17, 16, 16, 20, 18, 20, 20, 16, 20, 18, 20, 16, 16, 20, 14, 22, 26, 22, 18, 21, 24, 22, 20, 16, 20, 20, 28, 26, 26, 17, 20, 22, 26, 16, 24, 14, 18, 24, 24, 20, 14, 22, 26, 16, 24, 20
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OFFSET
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1,1
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COMMENTS
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If a(n) is a record, then the n-th prime is in sequence A090481.
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n) = A000005(A006093(n)) + A000005(A008864(n)). - R. J. Mathar, Mar 03 2010
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MAPLE
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taudiff := proc(n) numtheory[tau](n-1)+numtheory[tau](n+1) ; end proc: A175144 := proc(n) taudiff(ithprime(n)) ; end proc: seq(A175144(n), n=1..80) ; # R. J. Mathar, Mar 03 2010
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MATHEMATICA
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Table[p = Prime[n]; DivisorSigma[0, p - 1] + DivisorSigma[0, p + 1], {n, 100}]
Total[DivisorSigma[0, {#-1, #+1}]]&/@Prime[Range[80]] (* Harvey P. Dale, Feb 25 2012 *)
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CROSSREFS
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Cf. A000005, A090481, A090482, A175146.
Sequence in context: A120212 A093670 A185011 * A183054 A188569 A274140
Adjacent sequences: A175141 A175142 A175143 * A175145 A175146 A175147
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet, Feb 24 2010
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EXTENSIONS
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More terms from R. J. Mathar, Mar 03 2010
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STATUS
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approved
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