1,1
Table of n, a(n) for n=1..4.
Cf. A053067, A053068. Mersenne primes: A000668.
Sequence in context: A300947 A013826 A255012 * A100407 A332173 A119264
Adjacent sequences: A133011 A133012 A133013 * A133015 A133016 A133017
easy,nonn,base
Omar E. Pol, Oct 19 2007
approved