OFFSET
1,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
FORMULA
EXAMPLE
a(2) = (2+2) - 2 = 2 - for prime 3
a(3) = (2+3) - (2+2) = 1 - for prime 5
a(4) = (2+2+2) - (2+3) = 1 - for prime 7
a(5) = (2+2+3) - (2+5) = 0 - for prime 11
MAPLE
MATHEMATICA
a = {2}; b[n_] := Sum[FactorInteger[n][[i, 1]]*FactorInteger[n][[i, 2]], {i, 1, Length[FactorInteger[n]]}];; Do[AppendTo[a, b[Prime[n] + 1] - b[Prime[n] - 1]], {n, 2, 70}]; a (* Stefan Steinerberger, Jan 18 2008 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Alexander R. Povolotsky, Dec 31 2007, corrected Jan 03 2007
EXTENSIONS
More terms from R. J. Mathar and Stefan Steinerberger, Jan 18 2008
STATUS
approved