Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A078809
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A078809 Number of divisors of the average of consecutive odd primes. +0
1
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 (list; graph; listen)
OFFSET

1,1

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}]

CROSSREFS

Sequence in context: A104076 A021295 A061112 this_sequence A097857 A110738 A175028

Adjacent sequences: A078806 A078807 A078808 this_sequence A078810 A078811 A078812

KEYWORD

easy,nonn

AUTHOR

Joseph L. Pe (Joseph_l_pe(AT)hotmail.com), Jan 11 2003

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified December 2 11:54 EST 2009. Contains 167921 sequences.


AT&T Labs Research