OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; MoebiusMu[Select[Range[4000], midQ]] (* Amiram Eldar, Nov 03 2019 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Reinhard Zumkeller, Nov 29 2002
STATUS
approved