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A175144 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. 6
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a(n) is a record, then the n-th prime is in sequence A090481.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A000005(A006093(n)) + A000005(A008864(n)). - R. J. Mathar, Mar 03 2010

MAPLE

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

MATHEMATICA

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 *)

CROSSREFS

Cf. A000005, A090481, A090482, A175146.

Sequence in context: A120212 A093670 A185011 * A183054 A188569 A274140

Adjacent sequences:  A175141 A175142 A175143 * A175145 A175146 A175147

KEYWORD

nonn

AUTHOR

Leroy Quet, Feb 24 2010

EXTENSIONS

More terms from R. J. Mathar, Mar 03 2010

STATUS

approved

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Last modified August 14 01:00 EDT 2020. Contains 336473 sequences. (Running on oeis4.)