A078809 Number of divisors of the average of consecutive odd primes.

3, 4, 3, 6, 4, 6, 4, 4, 8, 4, 4, 8, 6, 6, 8, 12, 7, 4, 12, 6, 5, 4, 4, 6, 8, 8, 12, 4, 16, 4, 4, 8, 15, 12, 8, 12, 8, 8, 10, 18, 8, 14, 8, 12, 4, 4, 9, 12, 8, 6, 20, 8, 4, 12, 8, 16, 4, 6, 8, 18, 18, 4, 16, 12, 15, 4, 12, 12, 8, 6, 6, 8, 8, 4, 4, 4, 8, 10, 12, 24, 8, 20, 6, 9, 4, 4, 8, 16, 8, 4, 8, 4

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

The first pair of consecutive odd primes is 3,5, with average = 4 and tau(4) = 3. Hence a(1) = 3. The second pair of consecutive odd primes is 5,7, with average = 6 and tau(6) = 4, so a(2) = 4.

Mathematica

Table[DivisorSigma[0, (Prime[i] + Prime[i + 1])/2], {i, 2, 101}]
DivisorSigma[0, #]&/@(Mean/@Partition[Prime[Range[2, 100]], 2, 1]) (* Harvey P. Dale, Jul 06 2021 *)

Crossrefs

Sequence in context: A242801 A021295 A061112 * A245218 A097857 A176058

Adjacent sequences: A078806 A078807 A078808 * A078810 A078811 A078812

Keyword

easy,nonn

Author

Joseph L. Pe, Jan 11 2003

Status

approved