|
| |
|
|
A145337
|
|
a(n) = d(p(n)+1) - d(p(n)-1) (d(m) = the number of divisors of m, p(n)= the n-th prime.)
|
|
2
| |
|
|
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; 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). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 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: for n from 1 to 300 do printf("%d, ", A145337(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 10 2008]
|
|
|
MATHEMATICA
| DivisorSigma[0, #+1]-DivisorSigma[0, #-1]&/@Prime[Range[80]] (* From Harvey P. Dale, Nov 01 2011 *)
|
|
|
CROSSREFS
| A008328, A008329, A145338, A067889, A103664, A103665
Sequence in context: A065177 A064044 A144912 * 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 (mathar(AT)strw.leidenuniv.nl) and Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 10 2008
|
| |
|
|
