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A145337
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a(n) = d(p(n)+1) - d(p(n)-1) (d(m) = the number of divisors of m, p(n)= the n-th prime.)
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2
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1, 1, 1, 0, 2, -2, 1, 0, 4, 2, -2, -5, 0, -2, 6, 2, 8, -8, -2, 4, -8, 2, 8, 4, -6, -1, 0, 8, -4, -2, -4, 4, 0, 4, 6, -4, -8, -4, 12, 2, 14, -10, 6, -10, 3, 0, -10, 4, 8, -4, 4, 12, -14, 10, -1, 12, 10, -6, -8, -8, -2, 6, 0, 8, -12, 2, -10, -14, 8, 0, -4, 20, 2, -4, -4, 12, 10, -14, -7, -8
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OFFSET
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0,5
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 0..1000
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FORMULA
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a(n)=A008329(n)-A008328(n). [From R. J. Mathar, Oct 10 2008]
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MAPLE
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A000005 := proc(n) numtheory[tau](n) ; end: A008328 := proc(n) A000005(ithprime(n)-1) ; end: A008329 := proc(n) A000005(ithprime(n)+1) ; end: A145337 := proc(n) A008329(n)-A008328(n) ; end: for n from 1 to 300 do printf("%d, ", A145337(n)) ; od: [From R. J. Mathar, Oct 10 2008]
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MATHEMATICA
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DivisorSigma[0, #+1]-DivisorSigma[0, #-1]&/@Prime[Range[80]] (* From Harvey P. Dale, Nov 01 2011 *)
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CROSSREFS
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A008328, A008329, A145338, A067889, A103664, A103665
Sequence in context: A064044 A213980 A144912 * A171941 A071464 A071510
Adjacent sequences: A145334 A145335 A145336 * A145338 A145339 A145340
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KEYWORD
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sign
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AUTHOR
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Leroy Quet Oct 08 2008
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EXTENSIONS
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More terms from R. J. Mathar and Ray Chandler, Oct 10 2008
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STATUS
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approved
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