1,2

3, 7, 17, 41 and 937 are primes.

a(12) = 1 + 2 + 4 + 10 + 24 + 46 + 100 + 225 + 525 + 1225 + 3136 + 7056 = 12354.

Cf. A094837.

Sequence in context: A128647 A071730 A058815 this_sequence A089656 A018970 A018968

Adjacent sequences: A138898 A138899 A138900 this_sequence A138902 A138903 A138904

nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), May 16 2008