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A145337 a(n) = d(p(n)+1) - d(p(n)-1), where d(m) = the number of divisors of m, p(n) = the n-th prime. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = A008329(n) - A008328(n). - R. J. Mathar, Oct 10 2008

MAPLE

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: # R. J. Mathar, Oct 10 2008

MATHEMATICA

DivisorSigma[0, #+1]-DivisorSigma[0, #-1]&/@Prime[Range[80]] (* Harvey P. Dale, Nov 01 2011 *)

CROSSREFS

Cf. A008328, A008329, A067889, A103664, A103665, A145338.

Sequence in context: A213980 A144912 A306708 * A171941 A071464 A071510

Adjacent sequences:  A145334 A145335 A145336 * A145338 A145339 A145340

KEYWORD

sign

AUTHOR

Leroy Quet, Oct 08 2008

EXTENSIONS

More terms from R. J. Mathar and Ray Chandler, Oct 10 2008

STATUS

approved

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Last modified January 22 19:16 EST 2020. Contains 331153 sequences. (Running on oeis4.)