1,1

a(3) = 1777 1 followed by three copies of 7. 1111 and 1333 are composite.

a(4) = 137373737 is 1 followed by four copies of 37.

Sequence in context: A105124 A034831 A142362 this_sequence A088295 A064748 A091814

Adjacent sequences: A112730 A112731 A112732 this_sequence A112734 A112735 A112736

base,more,nonn,dumb

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jan 02 2006