1,1

a(n) = 2*A000668(n).

Cf. A000668, A139256.

Sequence in context: A118432 A032404 A059954 this_sequence A056842 A130263 A077401

Adjacent sequences: A139254 A139255 A139256 this_sequence A139258 A139259 A139260

nonn

Omar E. Pol (info(AT)polprimos.com), Apr 23 2008