1,4

a(2*n) > 0 (Goldbach's conjecture).

T. D. Noe, Table of n, a(n) for n=1..10000

10 = 1+3^2 = 2+2^3 = 3+7 = 5+5, therefore a(10) = 4;

11 = 2+3^2 = 3+2^3 = 4+7, therefore a(11) = 3;

12 = 1+11 = 3+3^2 = 2^2+2^3 = 5+7, therefore a(12) = 4;

a(149)=0, as for all x<149: if x prime power then 149-x not.

Cf. A000961, A002375, A071331.

Cf. A061358, A109829.

Sequence in context: A063787 A129843 A050430 this_sequence A092333 A107452 A029213

Adjacent sequences: A071327 A071328 A071329 this_sequence A071331 A071332 A071333

nonn,nice

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 19 2002