1,1

2*30-1=59 prime, 2*30+1=61 prime

a=30; Select[Prime[Range[250]], PrimeQ[a*#-1]&&PrimeQ[a*#+1] &]

Adjacent sequences: A138247 A138248 A138249 this_sequence A138251 A138252 A138253

Sequence in context: A090700 A105889 A086085 this_sequence A077323 A072468 A062666

nonn

Vladimir Orlovsky (4vladimir(AT)gmail.com), May 05 2008