1,1

Primes can only occur for n=2^k. The next term (if it exists) has k>=21 (i.e. more than 10^6 decimal digits). - Don Reble (djr(AT)nk.ca), Apr 28 2004. [For the latest results about the search, see A171381. - N. J. A. Sloane, Jun 14 2010]

Table of n, a(n) for n=1..6.

a(3)=41 because it can be written as (3^4+1)/2=82/2.

A171381 is the main entry for this sequence. Cf. also A138083.

Sequence in context: A076725 A059917 A255963 * A042447 A176266 A075872

Adjacent sequences: A093622 A093623 A093624 * A093626 A093627 A093628

nonn,hard

Hugo Pfoertner, Apr 19 2004

Erroneous terms deleted by N. J. A. Sloane, Jun 14 2010

approved